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1
2718-2721
8 Find the values of x for which y = [x(x – 2)]2 is an increasing function 9 Prove that (24sin cos ) y θ = − θ + θ is an increasing function of θ in 0 2 , π  
1
2719-2722
Find the values of x for which y = [x(x – 2)]2 is an increasing function 9 Prove that (24sin cos ) y θ = − θ + θ is an increasing function of θ in 0 2 , π   Rationalised 2023-24 APPLICATION OF DERIVATIVES 159 10
1
2720-2723
9 Prove that (24sin cos ) y θ = − θ + θ is an increasing function of θ in 0 2 , π   Rationalised 2023-24 APPLICATION OF DERIVATIVES 159 10 Prove that the logarithmic function is increasing on (0, ∞)
1
2721-2724
Prove that (24sin cos ) y θ = − θ + θ is an increasing function of θ in 0 2 , π   Rationalised 2023-24 APPLICATION OF DERIVATIVES 159 10 Prove that the logarithmic function is increasing on (0, ∞) 11
1
2722-2725
Rationalised 2023-24 APPLICATION OF DERIVATIVES 159 10 Prove that the logarithmic function is increasing on (0, ∞) 11 Prove that the function f given by f(x) = x2 – x + 1 is neither strictly increasing nor decreasing on (– 1, 1)
1
2723-2726
Prove that the logarithmic function is increasing on (0, ∞) 11 Prove that the function f given by f(x) = x2 – x + 1 is neither strictly increasing nor decreasing on (– 1, 1) 12
1
2724-2727
11 Prove that the function f given by f(x) = x2 – x + 1 is neither strictly increasing nor decreasing on (– 1, 1) 12 Which of the following functions are decreasing on 0, 2 π
1
2725-2728
Prove that the function f given by f(x) = x2 – x + 1 is neither strictly increasing nor decreasing on (– 1, 1) 12 Which of the following functions are decreasing on 0, 2 π (A) cos x (B) cos 2x (C) cos 3x (D) tan x 13
1
2726-2729
12 Which of the following functions are decreasing on 0, 2 π (A) cos x (B) cos 2x (C) cos 3x (D) tan x 13 On which of the following intervals is the function f given by f (x) = x100 + sin x –1 decreasing
1
2727-2730
Which of the following functions are decreasing on 0, 2 π (A) cos x (B) cos 2x (C) cos 3x (D) tan x 13 On which of the following intervals is the function f given by f (x) = x100 + sin x –1 decreasing (A) (0,1) (B) π2, π (C) 0, 2 π (D) None of these 14
1
2728-2731
(A) cos x (B) cos 2x (C) cos 3x (D) tan x 13 On which of the following intervals is the function f given by f (x) = x100 + sin x –1 decreasing (A) (0,1) (B) π2, π (C) 0, 2 π (D) None of these 14 For what values of a the function f given by f (x) = x2 + ax + 1 is increasing on [1, 2]
1
2729-2732
On which of the following intervals is the function f given by f (x) = x100 + sin x –1 decreasing (A) (0,1) (B) π2, π (C) 0, 2 π (D) None of these 14 For what values of a the function f given by f (x) = x2 + ax + 1 is increasing on [1, 2] 15
1
2730-2733
(A) (0,1) (B) π2, π (C) 0, 2 π (D) None of these 14 For what values of a the function f given by f (x) = x2 + ax + 1 is increasing on [1, 2] 15 Let I be any interval disjoint from [–1, 1]
1
2731-2734
For what values of a the function f given by f (x) = x2 + ax + 1 is increasing on [1, 2] 15 Let I be any interval disjoint from [–1, 1] Prove that the function f given by 1 ( ) f x x x = + is increasing on I
1
2732-2735
15 Let I be any interval disjoint from [–1, 1] Prove that the function f given by 1 ( ) f x x x = + is increasing on I 16
1
2733-2736
Let I be any interval disjoint from [–1, 1] Prove that the function f given by 1 ( ) f x x x = + is increasing on I 16 Prove that the function f given by f (x) = log sin x is increasing on 0 2 , π   and decreasing on π π 2 ,  
1
2734-2737
Prove that the function f given by 1 ( ) f x x x = + is increasing on I 16 Prove that the function f given by f (x) = log sin x is increasing on 0 2 , π   and decreasing on π π 2 ,   17
1
2735-2738
16 Prove that the function f given by f (x) = log sin x is increasing on 0 2 , π   and decreasing on π π 2 ,   17 Prove that the function f given by f (x) = log |cos x| is decreasing on 0, 2 π       and increasing on 3 , 2 π2 π    
1
2736-2739
Prove that the function f given by f (x) = log sin x is increasing on 0 2 , π   and decreasing on π π 2 ,   17 Prove that the function f given by f (x) = log |cos x| is decreasing on 0, 2 π       and increasing on 3 , 2 π2 π     18
1
2737-2740
17 Prove that the function f given by f (x) = log |cos x| is decreasing on 0, 2 π       and increasing on 3 , 2 π2 π     18 Prove that the function given by f (x) = x3 – 3x2 + 3x – 100 is increasing in R
1
2738-2741
Prove that the function f given by f (x) = log |cos x| is decreasing on 0, 2 π       and increasing on 3 , 2 π2 π     18 Prove that the function given by f (x) = x3 – 3x2 + 3x – 100 is increasing in R 19
1
2739-2742
18 Prove that the function given by f (x) = x3 – 3x2 + 3x – 100 is increasing in R 19 The interval in which y = x2 e–x is increasing is (A) (– ∞, ∞) (B) (– 2, 0) (C) (2, ∞) (D) (0, 2) 6
1
2740-2743
Prove that the function given by f (x) = x3 – 3x2 + 3x – 100 is increasing in R 19 The interval in which y = x2 e–x is increasing is (A) (– ∞, ∞) (B) (– 2, 0) (C) (2, ∞) (D) (0, 2) 6 4 Maxima and Minima In this section, we will use the concept of derivatives to calculate the maximum or minimum values of various functions
1
2741-2744
19 The interval in which y = x2 e–x is increasing is (A) (– ∞, ∞) (B) (– 2, 0) (C) (2, ∞) (D) (0, 2) 6 4 Maxima and Minima In this section, we will use the concept of derivatives to calculate the maximum or minimum values of various functions In fact, we will find the ‘turning points’ of the graph of a function and thus find points at which the graph reaches its highest (or Rationalised 2023-24 MATHEMATICS 160 lowest) locally
1
2742-2745
The interval in which y = x2 e–x is increasing is (A) (– ∞, ∞) (B) (– 2, 0) (C) (2, ∞) (D) (0, 2) 6 4 Maxima and Minima In this section, we will use the concept of derivatives to calculate the maximum or minimum values of various functions In fact, we will find the ‘turning points’ of the graph of a function and thus find points at which the graph reaches its highest (or Rationalised 2023-24 MATHEMATICS 160 lowest) locally The knowledge of such points is very useful in sketching the graph of a given function
1
2743-2746
4 Maxima and Minima In this section, we will use the concept of derivatives to calculate the maximum or minimum values of various functions In fact, we will find the ‘turning points’ of the graph of a function and thus find points at which the graph reaches its highest (or Rationalised 2023-24 MATHEMATICS 160 lowest) locally The knowledge of such points is very useful in sketching the graph of a given function Further, we will also find the absolute maximum and absolute minimum of a function that are necessary for the solution of many applied problems
1
2744-2747
In fact, we will find the ‘turning points’ of the graph of a function and thus find points at which the graph reaches its highest (or Rationalised 2023-24 MATHEMATICS 160 lowest) locally The knowledge of such points is very useful in sketching the graph of a given function Further, we will also find the absolute maximum and absolute minimum of a function that are necessary for the solution of many applied problems (i)Let us consider the following problems that arise in day to day life
1
2745-2748
The knowledge of such points is very useful in sketching the graph of a given function Further, we will also find the absolute maximum and absolute minimum of a function that are necessary for the solution of many applied problems (i)Let us consider the following problems that arise in day to day life The profit from a grove of orange trees is given by P(x) = ax + bx2, where a,b are constants and x is the number of orange trees per acre
1
2746-2749
Further, we will also find the absolute maximum and absolute minimum of a function that are necessary for the solution of many applied problems (i)Let us consider the following problems that arise in day to day life The profit from a grove of orange trees is given by P(x) = ax + bx2, where a,b are constants and x is the number of orange trees per acre How many trees per acre will maximise the profit
1
2747-2750
(i)Let us consider the following problems that arise in day to day life The profit from a grove of orange trees is given by P(x) = ax + bx2, where a,b are constants and x is the number of orange trees per acre How many trees per acre will maximise the profit (ii) A ball, thrown into the air from a building 60 metres high, travels along a path given by 2 ( ) 60 x60 h x x = + − , where x is the horizontal distance from the building and h(x) is the height of the ball
1
2748-2751
The profit from a grove of orange trees is given by P(x) = ax + bx2, where a,b are constants and x is the number of orange trees per acre How many trees per acre will maximise the profit (ii) A ball, thrown into the air from a building 60 metres high, travels along a path given by 2 ( ) 60 x60 h x x = + − , where x is the horizontal distance from the building and h(x) is the height of the ball What is the maximum height the ball will reach
1
2749-2752
How many trees per acre will maximise the profit (ii) A ball, thrown into the air from a building 60 metres high, travels along a path given by 2 ( ) 60 x60 h x x = + − , where x is the horizontal distance from the building and h(x) is the height of the ball What is the maximum height the ball will reach (iii) An Apache helicopter of enemy is flying along the path given by the curve f (x) = x2 + 7
1
2750-2753
(ii) A ball, thrown into the air from a building 60 metres high, travels along a path given by 2 ( ) 60 x60 h x x = + − , where x is the horizontal distance from the building and h(x) is the height of the ball What is the maximum height the ball will reach (iii) An Apache helicopter of enemy is flying along the path given by the curve f (x) = x2 + 7 A soldier, placed at the point (1, 2), wants to shoot the helicopter when it is nearest to him
1
2751-2754
What is the maximum height the ball will reach (iii) An Apache helicopter of enemy is flying along the path given by the curve f (x) = x2 + 7 A soldier, placed at the point (1, 2), wants to shoot the helicopter when it is nearest to him What is the nearest distance
1
2752-2755
(iii) An Apache helicopter of enemy is flying along the path given by the curve f (x) = x2 + 7 A soldier, placed at the point (1, 2), wants to shoot the helicopter when it is nearest to him What is the nearest distance In each of the above problem, there is something common, i
1
2753-2756
A soldier, placed at the point (1, 2), wants to shoot the helicopter when it is nearest to him What is the nearest distance In each of the above problem, there is something common, i e
1
2754-2757
What is the nearest distance In each of the above problem, there is something common, i e , we wish to find out the maximum or minimum values of the given functions
1
2755-2758
In each of the above problem, there is something common, i e , we wish to find out the maximum or minimum values of the given functions In order to tackle such problems, we first formally define maximum or minimum values of a function, points of local maxima and minima and test for determining such points
1
2756-2759
e , we wish to find out the maximum or minimum values of the given functions In order to tackle such problems, we first formally define maximum or minimum values of a function, points of local maxima and minima and test for determining such points Definition 3 Let f be a function defined on an interval I
1
2757-2760
, we wish to find out the maximum or minimum values of the given functions In order to tackle such problems, we first formally define maximum or minimum values of a function, points of local maxima and minima and test for determining such points Definition 3 Let f be a function defined on an interval I Then (a) f is said to have a maximum value in I, if there exists a point c in I such that ( ) ( ) f c> f x , for all x ∈ I
1
2758-2761
In order to tackle such problems, we first formally define maximum or minimum values of a function, points of local maxima and minima and test for determining such points Definition 3 Let f be a function defined on an interval I Then (a) f is said to have a maximum value in I, if there exists a point c in I such that ( ) ( ) f c> f x , for all x ∈ I The number f (c) is called the maximum value of f in I and the point c is called a point of maximum value of f in I
1
2759-2762
Definition 3 Let f be a function defined on an interval I Then (a) f is said to have a maximum value in I, if there exists a point c in I such that ( ) ( ) f c> f x , for all x ∈ I The number f (c) is called the maximum value of f in I and the point c is called a point of maximum value of f in I (b) f is said to have a minimum value in I, if there exists a point c in I such that f (c) < f (x), for all x ∈ I
1
2760-2763
Then (a) f is said to have a maximum value in I, if there exists a point c in I such that ( ) ( ) f c> f x , for all x ∈ I The number f (c) is called the maximum value of f in I and the point c is called a point of maximum value of f in I (b) f is said to have a minimum value in I, if there exists a point c in I such that f (c) < f (x), for all x ∈ I The number f (c), in this case, is called the minimum value of f in I and the point c, in this case, is called a point of minimum value of f in I
1
2761-2764
The number f (c) is called the maximum value of f in I and the point c is called a point of maximum value of f in I (b) f is said to have a minimum value in I, if there exists a point c in I such that f (c) < f (x), for all x ∈ I The number f (c), in this case, is called the minimum value of f in I and the point c, in this case, is called a point of minimum value of f in I (c) f is said to have an extreme value in I if there exists a point c in I such that f (c) is either a maximum value or a minimum value of f in I
1
2762-2765
(b) f is said to have a minimum value in I, if there exists a point c in I such that f (c) < f (x), for all x ∈ I The number f (c), in this case, is called the minimum value of f in I and the point c, in this case, is called a point of minimum value of f in I (c) f is said to have an extreme value in I if there exists a point c in I such that f (c) is either a maximum value or a minimum value of f in I The number f (c), in this case, is called an extreme value of f in I and the point c is called an extreme point
1
2763-2766
The number f (c), in this case, is called the minimum value of f in I and the point c, in this case, is called a point of minimum value of f in I (c) f is said to have an extreme value in I if there exists a point c in I such that f (c) is either a maximum value or a minimum value of f in I The number f (c), in this case, is called an extreme value of f in I and the point c is called an extreme point Remark In Fig 6
1
2764-2767
(c) f is said to have an extreme value in I if there exists a point c in I such that f (c) is either a maximum value or a minimum value of f in I The number f (c), in this case, is called an extreme value of f in I and the point c is called an extreme point Remark In Fig 6 7(a), (b) and (c), we have exhibited that graphs of certain particular functions help us to find maximum value and minimum value at a point
1
2765-2768
The number f (c), in this case, is called an extreme value of f in I and the point c is called an extreme point Remark In Fig 6 7(a), (b) and (c), we have exhibited that graphs of certain particular functions help us to find maximum value and minimum value at a point Infact, through graphs, we can even find maximum/minimum value of a function at a point at which it is not even differentiable (Example 15)
1
2766-2769
Remark In Fig 6 7(a), (b) and (c), we have exhibited that graphs of certain particular functions help us to find maximum value and minimum value at a point Infact, through graphs, we can even find maximum/minimum value of a function at a point at which it is not even differentiable (Example 15) Rationalised 2023-24 APPLICATION OF DERIVATIVES 161 Fig 6
1
2767-2770
7(a), (b) and (c), we have exhibited that graphs of certain particular functions help us to find maximum value and minimum value at a point Infact, through graphs, we can even find maximum/minimum value of a function at a point at which it is not even differentiable (Example 15) Rationalised 2023-24 APPLICATION OF DERIVATIVES 161 Fig 6 7 Example 14 Find the maximum and the minimum values, if any, of the function f given by f (x) = x2, x ∈ R
1
2768-2771
Infact, through graphs, we can even find maximum/minimum value of a function at a point at which it is not even differentiable (Example 15) Rationalised 2023-24 APPLICATION OF DERIVATIVES 161 Fig 6 7 Example 14 Find the maximum and the minimum values, if any, of the function f given by f (x) = x2, x ∈ R Solution From the graph of the given function (Fig 6
1
2769-2772
Rationalised 2023-24 APPLICATION OF DERIVATIVES 161 Fig 6 7 Example 14 Find the maximum and the minimum values, if any, of the function f given by f (x) = x2, x ∈ R Solution From the graph of the given function (Fig 6 8), we have f (x) = 0 if x = 0
1
2770-2773
7 Example 14 Find the maximum and the minimum values, if any, of the function f given by f (x) = x2, x ∈ R Solution From the graph of the given function (Fig 6 8), we have f (x) = 0 if x = 0 Also f (x) ≥ 0, for all x ∈ R
1
2771-2774
Solution From the graph of the given function (Fig 6 8), we have f (x) = 0 if x = 0 Also f (x) ≥ 0, for all x ∈ R Therefore, the minimum value of f is 0 and the point of minimum value of f is x = 0
1
2772-2775
8), we have f (x) = 0 if x = 0 Also f (x) ≥ 0, for all x ∈ R Therefore, the minimum value of f is 0 and the point of minimum value of f is x = 0 Further, it may be observed from the graph of the function that f has no maximum value and hence no point of maximum value of f in R
1
2773-2776
Also f (x) ≥ 0, for all x ∈ R Therefore, the minimum value of f is 0 and the point of minimum value of f is x = 0 Further, it may be observed from the graph of the function that f has no maximum value and hence no point of maximum value of f in R ANote If we restrict the domain of f to [– 2, 1] only, then f will have maximum value(– 2)2 = 4 at x = – 2
1
2774-2777
Therefore, the minimum value of f is 0 and the point of minimum value of f is x = 0 Further, it may be observed from the graph of the function that f has no maximum value and hence no point of maximum value of f in R ANote If we restrict the domain of f to [– 2, 1] only, then f will have maximum value(– 2)2 = 4 at x = – 2 Example 15 Find the maximum and minimum values of f , if any, of the function given by f(x) = |x|, x ∈ R
1
2775-2778
Further, it may be observed from the graph of the function that f has no maximum value and hence no point of maximum value of f in R ANote If we restrict the domain of f to [– 2, 1] only, then f will have maximum value(– 2)2 = 4 at x = – 2 Example 15 Find the maximum and minimum values of f , if any, of the function given by f(x) = |x|, x ∈ R Solution From the graph of the given function (Fig 6
1
2776-2779
ANote If we restrict the domain of f to [– 2, 1] only, then f will have maximum value(– 2)2 = 4 at x = – 2 Example 15 Find the maximum and minimum values of f , if any, of the function given by f(x) = |x|, x ∈ R Solution From the graph of the given function (Fig 6 9) , note that f (x) ≥ 0, for all x ∈ R and f (x) = 0 if x = 0
1
2777-2780
Example 15 Find the maximum and minimum values of f , if any, of the function given by f(x) = |x|, x ∈ R Solution From the graph of the given function (Fig 6 9) , note that f (x) ≥ 0, for all x ∈ R and f (x) = 0 if x = 0 Therefore, the function f has a minimum value 0 and the point of minimum value of f is x = 0
1
2778-2781
Solution From the graph of the given function (Fig 6 9) , note that f (x) ≥ 0, for all x ∈ R and f (x) = 0 if x = 0 Therefore, the function f has a minimum value 0 and the point of minimum value of f is x = 0 Also, the graph clearly shows that f has no maximum value in R and hence no point of maximum value in R
1
2779-2782
9) , note that f (x) ≥ 0, for all x ∈ R and f (x) = 0 if x = 0 Therefore, the function f has a minimum value 0 and the point of minimum value of f is x = 0 Also, the graph clearly shows that f has no maximum value in R and hence no point of maximum value in R ANote (i) If we restrict the domain of f to [– 2, 1] only, then f will have maximum value |– 2| = 2
1
2780-2783
Therefore, the function f has a minimum value 0 and the point of minimum value of f is x = 0 Also, the graph clearly shows that f has no maximum value in R and hence no point of maximum value in R ANote (i) If we restrict the domain of f to [– 2, 1] only, then f will have maximum value |– 2| = 2 Fig 6
1
2781-2784
Also, the graph clearly shows that f has no maximum value in R and hence no point of maximum value in R ANote (i) If we restrict the domain of f to [– 2, 1] only, then f will have maximum value |– 2| = 2 Fig 6 8 Fig 6
1
2782-2785
ANote (i) If we restrict the domain of f to [– 2, 1] only, then f will have maximum value |– 2| = 2 Fig 6 8 Fig 6 9 Rationalised 2023-24 MATHEMATICS 162 Fig 6
1
2783-2786
Fig 6 8 Fig 6 9 Rationalised 2023-24 MATHEMATICS 162 Fig 6 10 (ii) One may note that the function f in Example 27 is not differentiable at x = 0
1
2784-2787
8 Fig 6 9 Rationalised 2023-24 MATHEMATICS 162 Fig 6 10 (ii) One may note that the function f in Example 27 is not differentiable at x = 0 Example 16 Find the maximum and the minimum values, if any, of the function given by f (x) = x, x ∈ (0, 1)
1
2785-2788
9 Rationalised 2023-24 MATHEMATICS 162 Fig 6 10 (ii) One may note that the function f in Example 27 is not differentiable at x = 0 Example 16 Find the maximum and the minimum values, if any, of the function given by f (x) = x, x ∈ (0, 1) Solution The given function is an increasing (strictly) function in the given interval (0, 1)
1
2786-2789
10 (ii) One may note that the function f in Example 27 is not differentiable at x = 0 Example 16 Find the maximum and the minimum values, if any, of the function given by f (x) = x, x ∈ (0, 1) Solution The given function is an increasing (strictly) function in the given interval (0, 1) From the graph (Fig 6
1
2787-2790
Example 16 Find the maximum and the minimum values, if any, of the function given by f (x) = x, x ∈ (0, 1) Solution The given function is an increasing (strictly) function in the given interval (0, 1) From the graph (Fig 6 10) of the function f , it seems that, it should have the minimum value at a point closest to 0 on its right and the maximum value at a point closest to 1 on its left
1
2788-2791
Solution The given function is an increasing (strictly) function in the given interval (0, 1) From the graph (Fig 6 10) of the function f , it seems that, it should have the minimum value at a point closest to 0 on its right and the maximum value at a point closest to 1 on its left Are such points available
1
2789-2792
From the graph (Fig 6 10) of the function f , it seems that, it should have the minimum value at a point closest to 0 on its right and the maximum value at a point closest to 1 on its left Are such points available Of course, not
1
2790-2793
10) of the function f , it seems that, it should have the minimum value at a point closest to 0 on its right and the maximum value at a point closest to 1 on its left Are such points available Of course, not It is not possible to locate such points
1
2791-2794
Are such points available Of course, not It is not possible to locate such points Infact, if a point x0 is closest to 0, then we find 0 0 x2 <x for all 0 x ∈(0,1)
1
2792-2795
Of course, not It is not possible to locate such points Infact, if a point x0 is closest to 0, then we find 0 0 x2 <x for all 0 x ∈(0,1) Also, if x1 is closest to 1, then 1 1 x21 x + > for all 1 x ∈(0,1)
1
2793-2796
It is not possible to locate such points Infact, if a point x0 is closest to 0, then we find 0 0 x2 <x for all 0 x ∈(0,1) Also, if x1 is closest to 1, then 1 1 x21 x + > for all 1 x ∈(0,1) Therefore, the given function has neither the maximum value nor the minimum value in the interval (0,1)
1
2794-2797
Infact, if a point x0 is closest to 0, then we find 0 0 x2 <x for all 0 x ∈(0,1) Also, if x1 is closest to 1, then 1 1 x21 x + > for all 1 x ∈(0,1) Therefore, the given function has neither the maximum value nor the minimum value in the interval (0,1) Remark The reader may observe that in Example 16, if we include the points 0 and 1 in the domain of f , i
1
2795-2798
Also, if x1 is closest to 1, then 1 1 x21 x + > for all 1 x ∈(0,1) Therefore, the given function has neither the maximum value nor the minimum value in the interval (0,1) Remark The reader may observe that in Example 16, if we include the points 0 and 1 in the domain of f , i e
1
2796-2799
Therefore, the given function has neither the maximum value nor the minimum value in the interval (0,1) Remark The reader may observe that in Example 16, if we include the points 0 and 1 in the domain of f , i e , if we extend the domain of f to [0,1], then the function f has minimum value 0 at x = 0 and maximum value 1 at x = 1
1
2797-2800
Remark The reader may observe that in Example 16, if we include the points 0 and 1 in the domain of f , i e , if we extend the domain of f to [0,1], then the function f has minimum value 0 at x = 0 and maximum value 1 at x = 1 Infact, we have the following results (The proof of these results are beyond the scope of the present text) Every monotonic function assumes its maximum/minimum value at the end points of the domain of definition of the function
1
2798-2801
e , if we extend the domain of f to [0,1], then the function f has minimum value 0 at x = 0 and maximum value 1 at x = 1 Infact, we have the following results (The proof of these results are beyond the scope of the present text) Every monotonic function assumes its maximum/minimum value at the end points of the domain of definition of the function A more general result is Every continuous function on a closed interval has a maximum and a minimum value
1
2799-2802
, if we extend the domain of f to [0,1], then the function f has minimum value 0 at x = 0 and maximum value 1 at x = 1 Infact, we have the following results (The proof of these results are beyond the scope of the present text) Every monotonic function assumes its maximum/minimum value at the end points of the domain of definition of the function A more general result is Every continuous function on a closed interval has a maximum and a minimum value ANote By a monotonic function f in an interval I, we mean that f is either increasing in I or decreasing in I
1
2800-2803
Infact, we have the following results (The proof of these results are beyond the scope of the present text) Every monotonic function assumes its maximum/minimum value at the end points of the domain of definition of the function A more general result is Every continuous function on a closed interval has a maximum and a minimum value ANote By a monotonic function f in an interval I, we mean that f is either increasing in I or decreasing in I Maximum and minimum values of a function defined on a closed interval will be discussed later in this section
1
2801-2804
A more general result is Every continuous function on a closed interval has a maximum and a minimum value ANote By a monotonic function f in an interval I, we mean that f is either increasing in I or decreasing in I Maximum and minimum values of a function defined on a closed interval will be discussed later in this section Let us now examine the graph of a function as shown in Fig 6
1
2802-2805
ANote By a monotonic function f in an interval I, we mean that f is either increasing in I or decreasing in I Maximum and minimum values of a function defined on a closed interval will be discussed later in this section Let us now examine the graph of a function as shown in Fig 6 11
1
2803-2806
Maximum and minimum values of a function defined on a closed interval will be discussed later in this section Let us now examine the graph of a function as shown in Fig 6 11 Observe that at points A, B, C and D on the graph, the function changes its nature from decreasing to increasing or vice-versa
1
2804-2807
Let us now examine the graph of a function as shown in Fig 6 11 Observe that at points A, B, C and D on the graph, the function changes its nature from decreasing to increasing or vice-versa These points may be called turning points of the given function
1
2805-2808
11 Observe that at points A, B, C and D on the graph, the function changes its nature from decreasing to increasing or vice-versa These points may be called turning points of the given function Further, observe that at turning points, the graph has either a little hill or a little valley
1
2806-2809
Observe that at points A, B, C and D on the graph, the function changes its nature from decreasing to increasing or vice-versa These points may be called turning points of the given function Further, observe that at turning points, the graph has either a little hill or a little valley Roughly speaking, the function has minimum value in some neighbourhood (interval) of each of the points A and C which are at the bottom of their respective Rationalised 2023-24 APPLICATION OF DERIVATIVES 163 valleys
1
2807-2810
These points may be called turning points of the given function Further, observe that at turning points, the graph has either a little hill or a little valley Roughly speaking, the function has minimum value in some neighbourhood (interval) of each of the points A and C which are at the bottom of their respective Rationalised 2023-24 APPLICATION OF DERIVATIVES 163 valleys Similarly, the function has maximum value in some neighbourhood of points B and D which are at the top of their respective hills
1
2808-2811
Further, observe that at turning points, the graph has either a little hill or a little valley Roughly speaking, the function has minimum value in some neighbourhood (interval) of each of the points A and C which are at the bottom of their respective Rationalised 2023-24 APPLICATION OF DERIVATIVES 163 valleys Similarly, the function has maximum value in some neighbourhood of points B and D which are at the top of their respective hills For this reason, the points A and C may be regarded as points of local minimum value (or relative minimum value) and points B and D may be regarded as points of local maximum value (or relative maximum value) for the function
1
2809-2812
Roughly speaking, the function has minimum value in some neighbourhood (interval) of each of the points A and C which are at the bottom of their respective Rationalised 2023-24 APPLICATION OF DERIVATIVES 163 valleys Similarly, the function has maximum value in some neighbourhood of points B and D which are at the top of their respective hills For this reason, the points A and C may be regarded as points of local minimum value (or relative minimum value) and points B and D may be regarded as points of local maximum value (or relative maximum value) for the function The local maximum value and local minimum value of the function are referred to as local maxima and local minima, respectively, of the function
1
2810-2813
Similarly, the function has maximum value in some neighbourhood of points B and D which are at the top of their respective hills For this reason, the points A and C may be regarded as points of local minimum value (or relative minimum value) and points B and D may be regarded as points of local maximum value (or relative maximum value) for the function The local maximum value and local minimum value of the function are referred to as local maxima and local minima, respectively, of the function We now formally give the following definition Definition 4 Let f be a real valued function and let c be an interior point in the domain of f
1
2811-2814
For this reason, the points A and C may be regarded as points of local minimum value (or relative minimum value) and points B and D may be regarded as points of local maximum value (or relative maximum value) for the function The local maximum value and local minimum value of the function are referred to as local maxima and local minima, respectively, of the function We now formally give the following definition Definition 4 Let f be a real valued function and let c be an interior point in the domain of f Then (a) c is called a point of local maxima if there is an h > 0 such that f (c) ≥ f (x), for all x in (c – h, c + h), x ≠ c The value f (c) is called the local maximum value of f
1
2812-2815
The local maximum value and local minimum value of the function are referred to as local maxima and local minima, respectively, of the function We now formally give the following definition Definition 4 Let f be a real valued function and let c be an interior point in the domain of f Then (a) c is called a point of local maxima if there is an h > 0 such that f (c) ≥ f (x), for all x in (c – h, c + h), x ≠ c The value f (c) is called the local maximum value of f (b) c is called a point of local minima if there is an h > 0 such that f (c) ≤ f (x), for all x in (c – h, c + h) The value f (c) is called the local minimum value of f
1
2813-2816
We now formally give the following definition Definition 4 Let f be a real valued function and let c be an interior point in the domain of f Then (a) c is called a point of local maxima if there is an h > 0 such that f (c) ≥ f (x), for all x in (c – h, c + h), x ≠ c The value f (c) is called the local maximum value of f (b) c is called a point of local minima if there is an h > 0 such that f (c) ≤ f (x), for all x in (c – h, c + h) The value f (c) is called the local minimum value of f Geometrically, the above definition states that if x = c is a point of local maxima of f, then the graph of f around c will be as shown in Fig 6
1
2814-2817
Then (a) c is called a point of local maxima if there is an h > 0 such that f (c) ≥ f (x), for all x in (c – h, c + h), x ≠ c The value f (c) is called the local maximum value of f (b) c is called a point of local minima if there is an h > 0 such that f (c) ≤ f (x), for all x in (c – h, c + h) The value f (c) is called the local minimum value of f Geometrically, the above definition states that if x = c is a point of local maxima of f, then the graph of f around c will be as shown in Fig 6 12(a)
1
2815-2818
(b) c is called a point of local minima if there is an h > 0 such that f (c) ≤ f (x), for all x in (c – h, c + h) The value f (c) is called the local minimum value of f Geometrically, the above definition states that if x = c is a point of local maxima of f, then the graph of f around c will be as shown in Fig 6 12(a) Note that the function f is increasing (i
1
2816-2819
Geometrically, the above definition states that if x = c is a point of local maxima of f, then the graph of f around c will be as shown in Fig 6 12(a) Note that the function f is increasing (i e
1
2817-2820
12(a) Note that the function f is increasing (i e , f ′(x) > 0) in the interval (c – h, c) and decreasing (i