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1018-1021
An arrangement or display of the above kind is called a matrix Formally, we define matrix as: Definition 1 A matrix is an ordered rectangular array of numbers or functions The numbers or functions are called the elements or the entries of the matrix We denote matrices by capital letters
1
1019-1022
Formally, we define matrix as: Definition 1 A matrix is an ordered rectangular array of numbers or functions The numbers or functions are called the elements or the entries of the matrix We denote matrices by capital letters The following are some examples of matrices: 5 – 2 A 0 5 3 6     =       , 1 2 3 2 B 3
1
1020-1023
The numbers or functions are called the elements or the entries of the matrix We denote matrices by capital letters The following are some examples of matrices: 5 – 2 A 0 5 3 6     =       , 1 2 3 2 B 3 5 –1 2 5 3 5 7 i   + −     =         , 3 1 3 C cos tan sin 2 x x x x x   = +  +   In the above examples, the horizontal lines of elements are said to constitute, rows of the matrix and the vertical lines of elements are said to constitute, columns of the matrix
1
1021-1024
We denote matrices by capital letters The following are some examples of matrices: 5 – 2 A 0 5 3 6     =       , 1 2 3 2 B 3 5 –1 2 5 3 5 7 i   + −     =         , 3 1 3 C cos tan sin 2 x x x x x   = +  +   In the above examples, the horizontal lines of elements are said to constitute, rows of the matrix and the vertical lines of elements are said to constitute, columns of the matrix Thus A has 3 rows and 2 columns, B has 3 rows and 3 columns while C has 2 rows and 3 columns
1
1022-1025
The following are some examples of matrices: 5 – 2 A 0 5 3 6     =       , 1 2 3 2 B 3 5 –1 2 5 3 5 7 i   + −     =         , 3 1 3 C cos tan sin 2 x x x x x   = +  +   In the above examples, the horizontal lines of elements are said to constitute, rows of the matrix and the vertical lines of elements are said to constitute, columns of the matrix Thus A has 3 rows and 2 columns, B has 3 rows and 3 columns while C has 2 rows and 3 columns 3
1
1023-1026
5 –1 2 5 3 5 7 i   + −     =         , 3 1 3 C cos tan sin 2 x x x x x   = +  +   In the above examples, the horizontal lines of elements are said to constitute, rows of the matrix and the vertical lines of elements are said to constitute, columns of the matrix Thus A has 3 rows and 2 columns, B has 3 rows and 3 columns while C has 2 rows and 3 columns 3 2
1
1024-1027
Thus A has 3 rows and 2 columns, B has 3 rows and 3 columns while C has 2 rows and 3 columns 3 2 1 Order of a matrix A matrix having m rows and n columns is called a matrix of order m × n or simply m × n matrix (read as an m by n matrix)
1
1025-1028
3 2 1 Order of a matrix A matrix having m rows and n columns is called a matrix of order m × n or simply m × n matrix (read as an m by n matrix) So referring to the above examples of matrices, we have A as 3 × 2 matrix, B as 3 × 3 matrix and C as 2 × 3 matrix
1
1026-1029
2 1 Order of a matrix A matrix having m rows and n columns is called a matrix of order m × n or simply m × n matrix (read as an m by n matrix) So referring to the above examples of matrices, we have A as 3 × 2 matrix, B as 3 × 3 matrix and C as 2 × 3 matrix We observe that A has 3 × 2 = 6 elements, B and C have 9 and 6 elements, respectively
1
1027-1030
1 Order of a matrix A matrix having m rows and n columns is called a matrix of order m × n or simply m × n matrix (read as an m by n matrix) So referring to the above examples of matrices, we have A as 3 × 2 matrix, B as 3 × 3 matrix and C as 2 × 3 matrix We observe that A has 3 × 2 = 6 elements, B and C have 9 and 6 elements, respectively In general, an m × n matrix has the following rectangular array: or A = [aij]m × n, 1≤ i ≤ m, 1≤ j ≤ n i, j ∈ N Thus the ith row consists of the elements ai1, ai2, ai3,
1
1028-1031
So referring to the above examples of matrices, we have A as 3 × 2 matrix, B as 3 × 3 matrix and C as 2 × 3 matrix We observe that A has 3 × 2 = 6 elements, B and C have 9 and 6 elements, respectively In general, an m × n matrix has the following rectangular array: or A = [aij]m × n, 1≤ i ≤ m, 1≤ j ≤ n i, j ∈ N Thus the ith row consists of the elements ai1, ai2, ai3, , ain, while the jth column consists of the elements a1j, a2j, a3j,
1
1029-1032
We observe that A has 3 × 2 = 6 elements, B and C have 9 and 6 elements, respectively In general, an m × n matrix has the following rectangular array: or A = [aij]m × n, 1≤ i ≤ m, 1≤ j ≤ n i, j ∈ N Thus the ith row consists of the elements ai1, ai2, ai3, , ain, while the jth column consists of the elements a1j, a2j, a3j, , amj, In general aij, is an element lying in the ith row and jth column
1
1030-1033
In general, an m × n matrix has the following rectangular array: or A = [aij]m × n, 1≤ i ≤ m, 1≤ j ≤ n i, j ∈ N Thus the ith row consists of the elements ai1, ai2, ai3, , ain, while the jth column consists of the elements a1j, a2j, a3j, , amj, In general aij, is an element lying in the ith row and jth column We can also call it as the (i, j)th element of A
1
1031-1034
, ain, while the jth column consists of the elements a1j, a2j, a3j, , amj, In general aij, is an element lying in the ith row and jth column We can also call it as the (i, j)th element of A The number of elements in an m × n matrix will be equal to mn
1
1032-1035
, amj, In general aij, is an element lying in the ith row and jth column We can also call it as the (i, j)th element of A The number of elements in an m × n matrix will be equal to mn Rationalised 2023-24 MATRICES 37 ANote In this chapter 1
1
1033-1036
We can also call it as the (i, j)th element of A The number of elements in an m × n matrix will be equal to mn Rationalised 2023-24 MATRICES 37 ANote In this chapter 1 We shall follow the notation, namely A = [aij]m × n to indicate that A is a matrix of order m × n
1
1034-1037
The number of elements in an m × n matrix will be equal to mn Rationalised 2023-24 MATRICES 37 ANote In this chapter 1 We shall follow the notation, namely A = [aij]m × n to indicate that A is a matrix of order m × n 2
1
1035-1038
Rationalised 2023-24 MATRICES 37 ANote In this chapter 1 We shall follow the notation, namely A = [aij]m × n to indicate that A is a matrix of order m × n 2 We shall consider only those matrices whose elements are real numbers or functions taking real values
1
1036-1039
We shall follow the notation, namely A = [aij]m × n to indicate that A is a matrix of order m × n 2 We shall consider only those matrices whose elements are real numbers or functions taking real values We can also represent any point (x, y) in a plane by a matrix (column or row) as x y       (or [x, y])
1
1037-1040
2 We shall consider only those matrices whose elements are real numbers or functions taking real values We can also represent any point (x, y) in a plane by a matrix (column or row) as x y       (or [x, y]) For example point P(0, 1) as a matrix representation may be given as 0 P 1   =     or [0 1]
1
1038-1041
We shall consider only those matrices whose elements are real numbers or functions taking real values We can also represent any point (x, y) in a plane by a matrix (column or row) as x y       (or [x, y]) For example point P(0, 1) as a matrix representation may be given as 0 P 1   =     or [0 1] Observe that in this way we can also express the vertices of a closed rectilinear figure in the form of a matrix
1
1039-1042
We can also represent any point (x, y) in a plane by a matrix (column or row) as x y       (or [x, y]) For example point P(0, 1) as a matrix representation may be given as 0 P 1   =     or [0 1] Observe that in this way we can also express the vertices of a closed rectilinear figure in the form of a matrix For example, consider a quadrilateral ABCD with vertices A (1, 0), B (3, 2), C (1, 3), D (–1, 2)
1
1040-1043
For example point P(0, 1) as a matrix representation may be given as 0 P 1   =     or [0 1] Observe that in this way we can also express the vertices of a closed rectilinear figure in the form of a matrix For example, consider a quadrilateral ABCD with vertices A (1, 0), B (3, 2), C (1, 3), D (–1, 2) Now, quadrilateral ABCD in the matrix form, can be represented as 2 4 A B C D 1 3 1 1 X 0 2 3 2 × −   =     or 4 2 A 1 0 B 3 2 Y C 1 3 D 1 2 ×       =     −  Thus, matrices can be used as representation of vertices of geometrical figures in a plane
1
1041-1044
Observe that in this way we can also express the vertices of a closed rectilinear figure in the form of a matrix For example, consider a quadrilateral ABCD with vertices A (1, 0), B (3, 2), C (1, 3), D (–1, 2) Now, quadrilateral ABCD in the matrix form, can be represented as 2 4 A B C D 1 3 1 1 X 0 2 3 2 × −   =     or 4 2 A 1 0 B 3 2 Y C 1 3 D 1 2 ×       =     −  Thus, matrices can be used as representation of vertices of geometrical figures in a plane Now, let us consider some examples
1
1042-1045
For example, consider a quadrilateral ABCD with vertices A (1, 0), B (3, 2), C (1, 3), D (–1, 2) Now, quadrilateral ABCD in the matrix form, can be represented as 2 4 A B C D 1 3 1 1 X 0 2 3 2 × −   =     or 4 2 A 1 0 B 3 2 Y C 1 3 D 1 2 ×       =     −  Thus, matrices can be used as representation of vertices of geometrical figures in a plane Now, let us consider some examples Example 1 Consider the following information regarding the number of men and women workers in three factories I, II and III Men workers Women workers I 30 25 II 25 31 III 27 26 Represent the above information in the form of a 3 × 2 matrix
1
1043-1046
Now, quadrilateral ABCD in the matrix form, can be represented as 2 4 A B C D 1 3 1 1 X 0 2 3 2 × −   =     or 4 2 A 1 0 B 3 2 Y C 1 3 D 1 2 ×       =     −  Thus, matrices can be used as representation of vertices of geometrical figures in a plane Now, let us consider some examples Example 1 Consider the following information regarding the number of men and women workers in three factories I, II and III Men workers Women workers I 30 25 II 25 31 III 27 26 Represent the above information in the form of a 3 × 2 matrix What does the entry in the third row and second column represent
1
1044-1047
Now, let us consider some examples Example 1 Consider the following information regarding the number of men and women workers in three factories I, II and III Men workers Women workers I 30 25 II 25 31 III 27 26 Represent the above information in the form of a 3 × 2 matrix What does the entry in the third row and second column represent Rationalised 2023-24 38 MATHEMATICS Solution The information is represented in the form of a 3 × 2 matrix as follows: 30 25 A 25 31 27 26     =       The entry in the third row and second column represents the number of women workers in factory III
1
1045-1048
Example 1 Consider the following information regarding the number of men and women workers in three factories I, II and III Men workers Women workers I 30 25 II 25 31 III 27 26 Represent the above information in the form of a 3 × 2 matrix What does the entry in the third row and second column represent Rationalised 2023-24 38 MATHEMATICS Solution The information is represented in the form of a 3 × 2 matrix as follows: 30 25 A 25 31 27 26     =       The entry in the third row and second column represents the number of women workers in factory III Example 2 If a matrix has 8 elements, what are the possible orders it can have
1
1046-1049
What does the entry in the third row and second column represent Rationalised 2023-24 38 MATHEMATICS Solution The information is represented in the form of a 3 × 2 matrix as follows: 30 25 A 25 31 27 26     =       The entry in the third row and second column represents the number of women workers in factory III Example 2 If a matrix has 8 elements, what are the possible orders it can have Solution We know that if a matrix is of order m × n, it has mn elements
1
1047-1050
Rationalised 2023-24 38 MATHEMATICS Solution The information is represented in the form of a 3 × 2 matrix as follows: 30 25 A 25 31 27 26     =       The entry in the third row and second column represents the number of women workers in factory III Example 2 If a matrix has 8 elements, what are the possible orders it can have Solution We know that if a matrix is of order m × n, it has mn elements Thus, to find all possible orders of a matrix with 8 elements, we will find all ordered pairs of natural numbers, whose product is 8
1
1048-1051
Example 2 If a matrix has 8 elements, what are the possible orders it can have Solution We know that if a matrix is of order m × n, it has mn elements Thus, to find all possible orders of a matrix with 8 elements, we will find all ordered pairs of natural numbers, whose product is 8 Thus, all possible ordered pairs are (1, 8), (8, 1), (4, 2), (2, 4) Hence, possible orders are 1 × 8, 8 ×1, 4 × 2, 2 × 4 Example 3 Construct a 3 × 2 matrix whose elements are given by 1 | 3 | 2 aij i j = −
1
1049-1052
Solution We know that if a matrix is of order m × n, it has mn elements Thus, to find all possible orders of a matrix with 8 elements, we will find all ordered pairs of natural numbers, whose product is 8 Thus, all possible ordered pairs are (1, 8), (8, 1), (4, 2), (2, 4) Hence, possible orders are 1 × 8, 8 ×1, 4 × 2, 2 × 4 Example 3 Construct a 3 × 2 matrix whose elements are given by 1 | 3 | 2 aij i j = − Solution In general a 3 × 2 matrix is given by 11 12 21 22 31 32 A a a a a a a     =      
1
1050-1053
Thus, to find all possible orders of a matrix with 8 elements, we will find all ordered pairs of natural numbers, whose product is 8 Thus, all possible ordered pairs are (1, 8), (8, 1), (4, 2), (2, 4) Hence, possible orders are 1 × 8, 8 ×1, 4 × 2, 2 × 4 Example 3 Construct a 3 × 2 matrix whose elements are given by 1 | 3 | 2 aij i j = − Solution In general a 3 × 2 matrix is given by 11 12 21 22 31 32 A a a a a a a     =       Now 1 | 3 | 2 aij i j = − , i = 1, 2, 3 and j = 1, 2
1
1051-1054
Thus, all possible ordered pairs are (1, 8), (8, 1), (4, 2), (2, 4) Hence, possible orders are 1 × 8, 8 ×1, 4 × 2, 2 × 4 Example 3 Construct a 3 × 2 matrix whose elements are given by 1 | 3 | 2 aij i j = − Solution In general a 3 × 2 matrix is given by 11 12 21 22 31 32 A a a a a a a     =       Now 1 | 3 | 2 aij i j = − , i = 1, 2, 3 and j = 1, 2 Therefore 11 1 |1 3 1| 1 2 a = − × = 12 1 5 2|1 3 2| 2 a = − × = 21 1 1 | 2 3 1| 2 2 a = − × = 22 1 | 2 3 2| 2 2 a = − × = 31 1 |3 3 1| 0 2 a = − × = 32 1 3 |3 3 2 | 2 2 a = − × = Hence the required matrix is given by 5 1 2 1 A 2 2 3 0 2       =        
1
1052-1055
Solution In general a 3 × 2 matrix is given by 11 12 21 22 31 32 A a a a a a a     =       Now 1 | 3 | 2 aij i j = − , i = 1, 2, 3 and j = 1, 2 Therefore 11 1 |1 3 1| 1 2 a = − × = 12 1 5 2|1 3 2| 2 a = − × = 21 1 1 | 2 3 1| 2 2 a = − × = 22 1 | 2 3 2| 2 2 a = − × = 31 1 |3 3 1| 0 2 a = − × = 32 1 3 |3 3 2 | 2 2 a = − × = Hence the required matrix is given by 5 1 2 1 A 2 2 3 0 2       =         Rationalised 2023-24 MATRICES 39 3
1
1053-1056
Now 1 | 3 | 2 aij i j = − , i = 1, 2, 3 and j = 1, 2 Therefore 11 1 |1 3 1| 1 2 a = − × = 12 1 5 2|1 3 2| 2 a = − × = 21 1 1 | 2 3 1| 2 2 a = − × = 22 1 | 2 3 2| 2 2 a = − × = 31 1 |3 3 1| 0 2 a = − × = 32 1 3 |3 3 2 | 2 2 a = − × = Hence the required matrix is given by 5 1 2 1 A 2 2 3 0 2       =         Rationalised 2023-24 MATRICES 39 3 3 Types of Matrices In this section, we shall discuss different types of matrices
1
1054-1057
Therefore 11 1 |1 3 1| 1 2 a = − × = 12 1 5 2|1 3 2| 2 a = − × = 21 1 1 | 2 3 1| 2 2 a = − × = 22 1 | 2 3 2| 2 2 a = − × = 31 1 |3 3 1| 0 2 a = − × = 32 1 3 |3 3 2 | 2 2 a = − × = Hence the required matrix is given by 5 1 2 1 A 2 2 3 0 2       =         Rationalised 2023-24 MATRICES 39 3 3 Types of Matrices In this section, we shall discuss different types of matrices (i) Column matrix A matrix is said to be a column matrix if it has only one column
1
1055-1058
Rationalised 2023-24 MATRICES 39 3 3 Types of Matrices In this section, we shall discuss different types of matrices (i) Column matrix A matrix is said to be a column matrix if it has only one column For example, 0 3 A 1 1/ 2         = −      is a column matrix of order 4 × 1
1
1056-1059
3 Types of Matrices In this section, we shall discuss different types of matrices (i) Column matrix A matrix is said to be a column matrix if it has only one column For example, 0 3 A 1 1/ 2         = −      is a column matrix of order 4 × 1 In general, A = [aij] m × 1 is a column matrix of order m × 1
1
1057-1060
(i) Column matrix A matrix is said to be a column matrix if it has only one column For example, 0 3 A 1 1/ 2         = −      is a column matrix of order 4 × 1 In general, A = [aij] m × 1 is a column matrix of order m × 1 (ii) Row matrix A matrix is said to be a row matrix if it has only one row
1
1058-1061
For example, 0 3 A 1 1/ 2         = −      is a column matrix of order 4 × 1 In general, A = [aij] m × 1 is a column matrix of order m × 1 (ii) Row matrix A matrix is said to be a row matrix if it has only one row For example, 1 4 1 B 5 2 3 2 ×   = −     is a row matrix
1
1059-1062
In general, A = [aij] m × 1 is a column matrix of order m × 1 (ii) Row matrix A matrix is said to be a row matrix if it has only one row For example, 1 4 1 B 5 2 3 2 ×   = −     is a row matrix In general, B = [bij] 1 × n is a row matrix of order 1 × n
1
1060-1063
(ii) Row matrix A matrix is said to be a row matrix if it has only one row For example, 1 4 1 B 5 2 3 2 ×   = −     is a row matrix In general, B = [bij] 1 × n is a row matrix of order 1 × n (iii) Square matrix A matrix in which the number of rows are equal to the number of columns, is said to be a square matrix
1
1061-1064
For example, 1 4 1 B 5 2 3 2 ×   = −     is a row matrix In general, B = [bij] 1 × n is a row matrix of order 1 × n (iii) Square matrix A matrix in which the number of rows are equal to the number of columns, is said to be a square matrix Thus an m × n matrix is said to be a square matrix if m = n and is known as a square matrix of order ‘n’
1
1062-1065
In general, B = [bij] 1 × n is a row matrix of order 1 × n (iii) Square matrix A matrix in which the number of rows are equal to the number of columns, is said to be a square matrix Thus an m × n matrix is said to be a square matrix if m = n and is known as a square matrix of order ‘n’ For example 3 1 0 3 A 3 2 1 42 3 1 −       =    −   is a square matrix of order 3
1
1063-1066
(iii) Square matrix A matrix in which the number of rows are equal to the number of columns, is said to be a square matrix Thus an m × n matrix is said to be a square matrix if m = n and is known as a square matrix of order ‘n’ For example 3 1 0 3 A 3 2 1 42 3 1 −       =    −   is a square matrix of order 3 In general, A = [aij] m × m is a square matrix of order m
1
1064-1067
Thus an m × n matrix is said to be a square matrix if m = n and is known as a square matrix of order ‘n’ For example 3 1 0 3 A 3 2 1 42 3 1 −       =    −   is a square matrix of order 3 In general, A = [aij] m × m is a square matrix of order m ANote If A = [aij] is a square matrix of order n, then elements (entries) a11, a22,
1
1065-1068
For example 3 1 0 3 A 3 2 1 42 3 1 −       =    −   is a square matrix of order 3 In general, A = [aij] m × m is a square matrix of order m ANote If A = [aij] is a square matrix of order n, then elements (entries) a11, a22, , ann are said to constitute the diagonal, of the matrix A
1
1066-1069
In general, A = [aij] m × m is a square matrix of order m ANote If A = [aij] is a square matrix of order n, then elements (entries) a11, a22, , ann are said to constitute the diagonal, of the matrix A Thus, if 1 3 1 A 2 4 1 3 5 6 −     = −      
1
1067-1070
ANote If A = [aij] is a square matrix of order n, then elements (entries) a11, a22, , ann are said to constitute the diagonal, of the matrix A Thus, if 1 3 1 A 2 4 1 3 5 6 −     = −       Then the elements of the diagonal of A are 1, 4, 6
1
1068-1071
, ann are said to constitute the diagonal, of the matrix A Thus, if 1 3 1 A 2 4 1 3 5 6 −     = −       Then the elements of the diagonal of A are 1, 4, 6 Rationalised 2023-24 40 MATHEMATICS (iv) Diagonal matrix A square matrix B = [bij] m × m is said to be a diagonal matrix if all its non diagonal elements are zero, that is a matrix B = [bij] m × m is said to be a diagonal matrix if bij = 0, when i ≠ j
1
1069-1072
Thus, if 1 3 1 A 2 4 1 3 5 6 −     = −       Then the elements of the diagonal of A are 1, 4, 6 Rationalised 2023-24 40 MATHEMATICS (iv) Diagonal matrix A square matrix B = [bij] m × m is said to be a diagonal matrix if all its non diagonal elements are zero, that is a matrix B = [bij] m × m is said to be a diagonal matrix if bij = 0, when i ≠ j For example, A = [4], 1 0 B 0 2 −  =     , 1
1
1070-1073
Then the elements of the diagonal of A are 1, 4, 6 Rationalised 2023-24 40 MATHEMATICS (iv) Diagonal matrix A square matrix B = [bij] m × m is said to be a diagonal matrix if all its non diagonal elements are zero, that is a matrix B = [bij] m × m is said to be a diagonal matrix if bij = 0, when i ≠ j For example, A = [4], 1 0 B 0 2 −  =     , 1 1 0 0 C 0 2 0 0 0 3 −    =       , are diagonal matrices of order 1, 2, 3, respectively
1
1071-1074
Rationalised 2023-24 40 MATHEMATICS (iv) Diagonal matrix A square matrix B = [bij] m × m is said to be a diagonal matrix if all its non diagonal elements are zero, that is a matrix B = [bij] m × m is said to be a diagonal matrix if bij = 0, when i ≠ j For example, A = [4], 1 0 B 0 2 −  =     , 1 1 0 0 C 0 2 0 0 0 3 −    =       , are diagonal matrices of order 1, 2, 3, respectively (v) Scalar matrix A diagonal matrix is said to be a scalar matrix if its diagonal elements are equal, that is, a square matrix B = [bij] n × n is said to be a scalar matrix if bij = 0, when i ≠ j bij = k, when i = j, for some constant k
1
1072-1075
For example, A = [4], 1 0 B 0 2 −  =     , 1 1 0 0 C 0 2 0 0 0 3 −    =       , are diagonal matrices of order 1, 2, 3, respectively (v) Scalar matrix A diagonal matrix is said to be a scalar matrix if its diagonal elements are equal, that is, a square matrix B = [bij] n × n is said to be a scalar matrix if bij = 0, when i ≠ j bij = k, when i = j, for some constant k For example A = [3], 1 0 B 0 1 −  =  −   , 3 0 0 C 0 3 0 0 0 3     =       are scalar matrices of order 1, 2 and 3, respectively
1
1073-1076
1 0 0 C 0 2 0 0 0 3 −    =       , are diagonal matrices of order 1, 2, 3, respectively (v) Scalar matrix A diagonal matrix is said to be a scalar matrix if its diagonal elements are equal, that is, a square matrix B = [bij] n × n is said to be a scalar matrix if bij = 0, when i ≠ j bij = k, when i = j, for some constant k For example A = [3], 1 0 B 0 1 −  =  −   , 3 0 0 C 0 3 0 0 0 3     =       are scalar matrices of order 1, 2 and 3, respectively (vi) Identity matrix A square matrix in which elements in the diagonal are all 1 and rest are all zero is called an identity matrix
1
1074-1077
(v) Scalar matrix A diagonal matrix is said to be a scalar matrix if its diagonal elements are equal, that is, a square matrix B = [bij] n × n is said to be a scalar matrix if bij = 0, when i ≠ j bij = k, when i = j, for some constant k For example A = [3], 1 0 B 0 1 −  =  −   , 3 0 0 C 0 3 0 0 0 3     =       are scalar matrices of order 1, 2 and 3, respectively (vi) Identity matrix A square matrix in which elements in the diagonal are all 1 and rest are all zero is called an identity matrix In other words, the square matrix A = [aij] n × n is an identity matrix, if 1 0if if ij i j a i j = =  ≠ 
1
1075-1078
For example A = [3], 1 0 B 0 1 −  =  −   , 3 0 0 C 0 3 0 0 0 3     =       are scalar matrices of order 1, 2 and 3, respectively (vi) Identity matrix A square matrix in which elements in the diagonal are all 1 and rest are all zero is called an identity matrix In other words, the square matrix A = [aij] n × n is an identity matrix, if 1 0if if ij i j a i j = =  ≠  We denote the identity matrix of order n by In
1
1076-1079
(vi) Identity matrix A square matrix in which elements in the diagonal are all 1 and rest are all zero is called an identity matrix In other words, the square matrix A = [aij] n × n is an identity matrix, if 1 0if if ij i j a i j = =  ≠  We denote the identity matrix of order n by In When order is clear from the context, we simply write it as I
1
1077-1080
In other words, the square matrix A = [aij] n × n is an identity matrix, if 1 0if if ij i j a i j = =  ≠  We denote the identity matrix of order n by In When order is clear from the context, we simply write it as I For example [1], 1 0 0 1       , 1 0 0 0 1 0 0 0 1           are identity matrices of order 1, 2 and 3, respectively
1
1078-1081
We denote the identity matrix of order n by In When order is clear from the context, we simply write it as I For example [1], 1 0 0 1       , 1 0 0 0 1 0 0 0 1           are identity matrices of order 1, 2 and 3, respectively Observe that a scalar matrix is an identity matrix when k = 1
1
1079-1082
When order is clear from the context, we simply write it as I For example [1], 1 0 0 1       , 1 0 0 0 1 0 0 0 1           are identity matrices of order 1, 2 and 3, respectively Observe that a scalar matrix is an identity matrix when k = 1 But every identity matrix is clearly a scalar matrix
1
1080-1083
For example [1], 1 0 0 1       , 1 0 0 0 1 0 0 0 1           are identity matrices of order 1, 2 and 3, respectively Observe that a scalar matrix is an identity matrix when k = 1 But every identity matrix is clearly a scalar matrix Rationalised 2023-24 MATRICES 41 (vii) Zero matrix A matrix is said to be zero matrix or null matrix if all its elements are zero
1
1081-1084
Observe that a scalar matrix is an identity matrix when k = 1 But every identity matrix is clearly a scalar matrix Rationalised 2023-24 MATRICES 41 (vii) Zero matrix A matrix is said to be zero matrix or null matrix if all its elements are zero For example, [0], 0 0 0 0       , 0 0 0 0 0 0       , [0, 0] are all zero matrices
1
1082-1085
But every identity matrix is clearly a scalar matrix Rationalised 2023-24 MATRICES 41 (vii) Zero matrix A matrix is said to be zero matrix or null matrix if all its elements are zero For example, [0], 0 0 0 0       , 0 0 0 0 0 0       , [0, 0] are all zero matrices We denote zero matrix by O
1
1083-1086
Rationalised 2023-24 MATRICES 41 (vii) Zero matrix A matrix is said to be zero matrix or null matrix if all its elements are zero For example, [0], 0 0 0 0       , 0 0 0 0 0 0       , [0, 0] are all zero matrices We denote zero matrix by O Its order will be clear from the context
1
1084-1087
For example, [0], 0 0 0 0       , 0 0 0 0 0 0       , [0, 0] are all zero matrices We denote zero matrix by O Its order will be clear from the context 3
1
1085-1088
We denote zero matrix by O Its order will be clear from the context 3 3
1
1086-1089
Its order will be clear from the context 3 3 1 Equality of matrices Definition 2 Two matrices A = [aij] and B = [bij] are said to be equal if (i) they are of the same order (ii) each element of A is equal to the corresponding element of B, that is aij = bij for all i and j
1
1087-1090
3 3 1 Equality of matrices Definition 2 Two matrices A = [aij] and B = [bij] are said to be equal if (i) they are of the same order (ii) each element of A is equal to the corresponding element of B, that is aij = bij for all i and j For example, 2 3 2 3 and 0 1 0 1             are equal matrices but 3 2 2 3 and 0 1 0 1             are not equal matrices
1
1088-1091
3 1 Equality of matrices Definition 2 Two matrices A = [aij] and B = [bij] are said to be equal if (i) they are of the same order (ii) each element of A is equal to the corresponding element of B, that is aij = bij for all i and j For example, 2 3 2 3 and 0 1 0 1             are equal matrices but 3 2 2 3 and 0 1 0 1             are not equal matrices Symbolically, if two matrices A and B are equal, we write A = B
1
1089-1092
1 Equality of matrices Definition 2 Two matrices A = [aij] and B = [bij] are said to be equal if (i) they are of the same order (ii) each element of A is equal to the corresponding element of B, that is aij = bij for all i and j For example, 2 3 2 3 and 0 1 0 1             are equal matrices but 3 2 2 3 and 0 1 0 1             are not equal matrices Symbolically, if two matrices A and B are equal, we write A = B If 1
1
1090-1093
For example, 2 3 2 3 and 0 1 0 1             are equal matrices but 3 2 2 3 and 0 1 0 1             are not equal matrices Symbolically, if two matrices A and B are equal, we write A = B If 1 5 0 2 6 3 2 x y z a b c −        =             , then x = – 1
1
1091-1094
Symbolically, if two matrices A and B are equal, we write A = B If 1 5 0 2 6 3 2 x y z a b c −        =             , then x = – 1 5, y = 0, z = 2, a = 6 , b = 3, c = 2 Example 4 If 3 4 2 7 0 6 3 2 6 1 0 6 3 2 2 3 21 0 2 4 21 0 x z y y a c b b + + − −         − − = − − +         − − + −     Find the values of a, b, c, x, y and z
1
1092-1095
If 1 5 0 2 6 3 2 x y z a b c −        =             , then x = – 1 5, y = 0, z = 2, a = 6 , b = 3, c = 2 Example 4 If 3 4 2 7 0 6 3 2 6 1 0 6 3 2 2 3 21 0 2 4 21 0 x z y y a c b b + + − −         − − = − − +         − − + −     Find the values of a, b, c, x, y and z Solution As the given matrices are equal, therefore, their corresponding elements must be equal
1
1093-1096
5 0 2 6 3 2 x y z a b c −        =             , then x = – 1 5, y = 0, z = 2, a = 6 , b = 3, c = 2 Example 4 If 3 4 2 7 0 6 3 2 6 1 0 6 3 2 2 3 21 0 2 4 21 0 x z y y a c b b + + − −         − − = − − +         − − + −     Find the values of a, b, c, x, y and z Solution As the given matrices are equal, therefore, their corresponding elements must be equal Comparing the corresponding elements, we get x + 3 = 0, z + 4 = 6, 2y – 7 = 3y – 2 a – 1 = – 3, 0 = 2c + 2 b – 3 = 2b + 4, Simplifying, we get a = – 2, b = – 7, c = – 1, x = – 3, y = –5, z = 2 Example 5 Find the values of a, b, c, and d from the following equation: 2 2 4 3 5 4 3 11 24 a b a b c d c d + − −     =     − +     Rationalised 2023-24 42 MATHEMATICS Solution By equality of two matrices, equating the corresponding elements, we get 2a + b = 4 5c – d = 11 a – 2b = – 3 4c + 3d = 24 Solving these equations, we get a = 1, b = 2, c = 3 and d = 4 EXERCISE 3
1
1094-1097
5, y = 0, z = 2, a = 6 , b = 3, c = 2 Example 4 If 3 4 2 7 0 6 3 2 6 1 0 6 3 2 2 3 21 0 2 4 21 0 x z y y a c b b + + − −         − − = − − +         − − + −     Find the values of a, b, c, x, y and z Solution As the given matrices are equal, therefore, their corresponding elements must be equal Comparing the corresponding elements, we get x + 3 = 0, z + 4 = 6, 2y – 7 = 3y – 2 a – 1 = – 3, 0 = 2c + 2 b – 3 = 2b + 4, Simplifying, we get a = – 2, b = – 7, c = – 1, x = – 3, y = –5, z = 2 Example 5 Find the values of a, b, c, and d from the following equation: 2 2 4 3 5 4 3 11 24 a b a b c d c d + − −     =     − +     Rationalised 2023-24 42 MATHEMATICS Solution By equality of two matrices, equating the corresponding elements, we get 2a + b = 4 5c – d = 11 a – 2b = – 3 4c + 3d = 24 Solving these equations, we get a = 1, b = 2, c = 3 and d = 4 EXERCISE 3 1 1
1
1095-1098
Solution As the given matrices are equal, therefore, their corresponding elements must be equal Comparing the corresponding elements, we get x + 3 = 0, z + 4 = 6, 2y – 7 = 3y – 2 a – 1 = – 3, 0 = 2c + 2 b – 3 = 2b + 4, Simplifying, we get a = – 2, b = – 7, c = – 1, x = – 3, y = –5, z = 2 Example 5 Find the values of a, b, c, and d from the following equation: 2 2 4 3 5 4 3 11 24 a b a b c d c d + − −     =     − +     Rationalised 2023-24 42 MATHEMATICS Solution By equality of two matrices, equating the corresponding elements, we get 2a + b = 4 5c – d = 11 a – 2b = – 3 4c + 3d = 24 Solving these equations, we get a = 1, b = 2, c = 3 and d = 4 EXERCISE 3 1 1 In the matrix 2 5 19 7 5 A 35 2 12 2 17 3 1 5   −     = −     −   , write: (i) The order of the matrix, (ii) The number of elements, (iii) Write the elements a13, a21, a33, a24, a23
1
1096-1099
Comparing the corresponding elements, we get x + 3 = 0, z + 4 = 6, 2y – 7 = 3y – 2 a – 1 = – 3, 0 = 2c + 2 b – 3 = 2b + 4, Simplifying, we get a = – 2, b = – 7, c = – 1, x = – 3, y = –5, z = 2 Example 5 Find the values of a, b, c, and d from the following equation: 2 2 4 3 5 4 3 11 24 a b a b c d c d + − −     =     − +     Rationalised 2023-24 42 MATHEMATICS Solution By equality of two matrices, equating the corresponding elements, we get 2a + b = 4 5c – d = 11 a – 2b = – 3 4c + 3d = 24 Solving these equations, we get a = 1, b = 2, c = 3 and d = 4 EXERCISE 3 1 1 In the matrix 2 5 19 7 5 A 35 2 12 2 17 3 1 5   −     = −     −   , write: (i) The order of the matrix, (ii) The number of elements, (iii) Write the elements a13, a21, a33, a24, a23 2
1
1097-1100
1 1 In the matrix 2 5 19 7 5 A 35 2 12 2 17 3 1 5   −     = −     −   , write: (i) The order of the matrix, (ii) The number of elements, (iii) Write the elements a13, a21, a33, a24, a23 2 If a matrix has 24 elements, what are the possible orders it can have
1
1098-1101
In the matrix 2 5 19 7 5 A 35 2 12 2 17 3 1 5   −     = −     −   , write: (i) The order of the matrix, (ii) The number of elements, (iii) Write the elements a13, a21, a33, a24, a23 2 If a matrix has 24 elements, what are the possible orders it can have What, if it has 13 elements
1
1099-1102
2 If a matrix has 24 elements, what are the possible orders it can have What, if it has 13 elements 3
1
1100-1103
If a matrix has 24 elements, what are the possible orders it can have What, if it has 13 elements 3 If a matrix has 18 elements, what are the possible orders it can have
1
1101-1104
What, if it has 13 elements 3 If a matrix has 18 elements, what are the possible orders it can have What, if it has 5 elements
1
1102-1105
3 If a matrix has 18 elements, what are the possible orders it can have What, if it has 5 elements 4
1
1103-1106
If a matrix has 18 elements, what are the possible orders it can have What, if it has 5 elements 4 Construct a 2 × 2 matrix, A = [aij], whose elements are given by: (i) 2 ( ) 2 ij i j a + = (ii) ij i a j = (iii) 2 ( 2 ) 2 ij i j a + = 5
1
1104-1107
What, if it has 5 elements 4 Construct a 2 × 2 matrix, A = [aij], whose elements are given by: (i) 2 ( ) 2 ij i j a + = (ii) ij i a j = (iii) 2 ( 2 ) 2 ij i j a + = 5 Construct a 3 × 4 matrix, whose elements are given by: (i) 1 | 3 | 2 aij i j = − + (ii) 2 aij i j = − 6
1
1105-1108
4 Construct a 2 × 2 matrix, A = [aij], whose elements are given by: (i) 2 ( ) 2 ij i j a + = (ii) ij i a j = (iii) 2 ( 2 ) 2 ij i j a + = 5 Construct a 3 × 4 matrix, whose elements are given by: (i) 1 | 3 | 2 aij i j = − + (ii) 2 aij i j = − 6 Find the values of x, y and z from the following equations: (i) 4 3 5 1 5 y z x    =         (ii) 2 6 2 5 5 8 x y z xy +    =     +    (iii) 9 5 7 x y z x z y z + +         + =         +     7
1
1106-1109
Construct a 2 × 2 matrix, A = [aij], whose elements are given by: (i) 2 ( ) 2 ij i j a + = (ii) ij i a j = (iii) 2 ( 2 ) 2 ij i j a + = 5 Construct a 3 × 4 matrix, whose elements are given by: (i) 1 | 3 | 2 aij i j = − + (ii) 2 aij i j = − 6 Find the values of x, y and z from the following equations: (i) 4 3 5 1 5 y z x    =         (ii) 2 6 2 5 5 8 x y z xy +    =     +    (iii) 9 5 7 x y z x z y z + +         + =         +     7 Find the value of a, b, c and d from the equation: 2 1 5 2 3 0 13 a b a c a b c d − + −     =     − +     Rationalised 2023-24 MATRICES 43 8
1
1107-1110
Construct a 3 × 4 matrix, whose elements are given by: (i) 1 | 3 | 2 aij i j = − + (ii) 2 aij i j = − 6 Find the values of x, y and z from the following equations: (i) 4 3 5 1 5 y z x    =         (ii) 2 6 2 5 5 8 x y z xy +    =     +    (iii) 9 5 7 x y z x z y z + +         + =         +     7 Find the value of a, b, c and d from the equation: 2 1 5 2 3 0 13 a b a c a b c d − + −     =     − +     Rationalised 2023-24 MATRICES 43 8 A = [aij]m × n\ is a square matrix, if (A) m < n (B) m > n (C) m = n (D) None of these 9
1
1108-1111
Find the values of x, y and z from the following equations: (i) 4 3 5 1 5 y z x    =         (ii) 2 6 2 5 5 8 x y z xy +    =     +    (iii) 9 5 7 x y z x z y z + +         + =         +     7 Find the value of a, b, c and d from the equation: 2 1 5 2 3 0 13 a b a c a b c d − + −     =     − +     Rationalised 2023-24 MATRICES 43 8 A = [aij]m × n\ is a square matrix, if (A) m < n (B) m > n (C) m = n (D) None of these 9 Which of the given values of x and y make the following pair of matrices equal 3 7 5 1 2 3 x y x +     + −   , 0 2 8 4 y −       (A) 1, 7 3 x y =− = (B) Not possible to find (C) y = 7, 32 x =− (D) 1 2 3, 3 x y − − = = 10
1
1109-1112
Find the value of a, b, c and d from the equation: 2 1 5 2 3 0 13 a b a c a b c d − + −     =     − +     Rationalised 2023-24 MATRICES 43 8 A = [aij]m × n\ is a square matrix, if (A) m < n (B) m > n (C) m = n (D) None of these 9 Which of the given values of x and y make the following pair of matrices equal 3 7 5 1 2 3 x y x +     + −   , 0 2 8 4 y −       (A) 1, 7 3 x y =− = (B) Not possible to find (C) y = 7, 32 x =− (D) 1 2 3, 3 x y − − = = 10 The number of all possible matrices of order 3 × 3 with each entry 0 or 1 is: (A) 27 (B) 18 (C) 81 (D) 512 3
1
1110-1113
A = [aij]m × n\ is a square matrix, if (A) m < n (B) m > n (C) m = n (D) None of these 9 Which of the given values of x and y make the following pair of matrices equal 3 7 5 1 2 3 x y x +     + −   , 0 2 8 4 y −       (A) 1, 7 3 x y =− = (B) Not possible to find (C) y = 7, 32 x =− (D) 1 2 3, 3 x y − − = = 10 The number of all possible matrices of order 3 × 3 with each entry 0 or 1 is: (A) 27 (B) 18 (C) 81 (D) 512 3 4 Operations on Matrices In this section, we shall introduce certain operations on matrices, namely, addition of matrices, multiplication of a matrix by a scalar, difference and multiplication of matrices
1
1111-1114
Which of the given values of x and y make the following pair of matrices equal 3 7 5 1 2 3 x y x +     + −   , 0 2 8 4 y −       (A) 1, 7 3 x y =− = (B) Not possible to find (C) y = 7, 32 x =− (D) 1 2 3, 3 x y − − = = 10 The number of all possible matrices of order 3 × 3 with each entry 0 or 1 is: (A) 27 (B) 18 (C) 81 (D) 512 3 4 Operations on Matrices In this section, we shall introduce certain operations on matrices, namely, addition of matrices, multiplication of a matrix by a scalar, difference and multiplication of matrices 3
1
1112-1115
The number of all possible matrices of order 3 × 3 with each entry 0 or 1 is: (A) 27 (B) 18 (C) 81 (D) 512 3 4 Operations on Matrices In this section, we shall introduce certain operations on matrices, namely, addition of matrices, multiplication of a matrix by a scalar, difference and multiplication of matrices 3 4
1
1113-1116
4 Operations on Matrices In this section, we shall introduce certain operations on matrices, namely, addition of matrices, multiplication of a matrix by a scalar, difference and multiplication of matrices 3 4 1 Addition of matrices Suppose Fatima has two factories at places A and B
1
1114-1117
3 4 1 Addition of matrices Suppose Fatima has two factories at places A and B Each factory produces sport shoes for boys and girls in three different price categories labelled 1, 2 and 3
1
1115-1118
4 1 Addition of matrices Suppose Fatima has two factories at places A and B Each factory produces sport shoes for boys and girls in three different price categories labelled 1, 2 and 3 The quantities produced by each factory are represented as matrices given below: Suppose Fatima wants to know the total production of sport shoes in each price category
1
1116-1119
1 Addition of matrices Suppose Fatima has two factories at places A and B Each factory produces sport shoes for boys and girls in three different price categories labelled 1, 2 and 3 The quantities produced by each factory are represented as matrices given below: Suppose Fatima wants to know the total production of sport shoes in each price category Then the total production In category 1 : for boys (80 + 90), for girls (60 + 50) In category 2 : for boys (75 + 70), for girls (65 + 55) In category 3 : for boys (90 + 75), for girls (85 + 75) This can be represented in the matrix form as 80 90 60 50 75 70 65 55 90 75 85 75 + +     + +     + +  
1
1117-1120
Each factory produces sport shoes for boys and girls in three different price categories labelled 1, 2 and 3 The quantities produced by each factory are represented as matrices given below: Suppose Fatima wants to know the total production of sport shoes in each price category Then the total production In category 1 : for boys (80 + 90), for girls (60 + 50) In category 2 : for boys (75 + 70), for girls (65 + 55) In category 3 : for boys (90 + 75), for girls (85 + 75) This can be represented in the matrix form as 80 90 60 50 75 70 65 55 90 75 85 75 + +     + +     + +   Rationalised 2023-24 44 MATHEMATICS This new matrix is the sum of the above two matrices