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3418-3421
INTEGRALS 299 10 The process of differentiation and integration are inverses of each other as discussed in Section 7 2 2 (i)
1
3419-3422
The process of differentiation and integration are inverses of each other as discussed in Section 7 2 2 (i) EXERCISE 7
1
3420-3423
2 2 (i) EXERCISE 7 1 Find an anti derivative (or integral) of the following functions by the method of inspection
1
3421-3424
2 (i) EXERCISE 7 1 Find an anti derivative (or integral) of the following functions by the method of inspection 1
1
3422-3425
EXERCISE 7 1 Find an anti derivative (or integral) of the following functions by the method of inspection 1 sin 2x 2
1
3423-3426
1 Find an anti derivative (or integral) of the following functions by the method of inspection 1 sin 2x 2 cos 3x 3
1
3424-3427
1 sin 2x 2 cos 3x 3 e 2x 4
1
3425-3428
sin 2x 2 cos 3x 3 e 2x 4 (ax + b)2 5
1
3426-3429
cos 3x 3 e 2x 4 (ax + b)2 5 sin 2x – 4 e3x Find the following integrals in Exercises 6 to 20: 6
1
3427-3430
e 2x 4 (ax + b)2 5 sin 2x – 4 e3x Find the following integrals in Exercises 6 to 20: 6 (4 3 ex+ 1) dx ∫ 7
1
3428-3431
(ax + b)2 5 sin 2x – 4 e3x Find the following integrals in Exercises 6 to 20: 6 (4 3 ex+ 1) dx ∫ 7 2 (1–12 ) x dx x ∫ 8
1
3429-3432
sin 2x – 4 e3x Find the following integrals in Exercises 6 to 20: 6 (4 3 ex+ 1) dx ∫ 7 2 (1–12 ) x dx x ∫ 8 2 ( ) ax bx c dx + + ∫ 9
1
3430-3433
(4 3 ex+ 1) dx ∫ 7 2 (1–12 ) x dx x ∫ 8 2 ( ) ax bx c dx + + ∫ 9 (22 x) x e dx + ∫ 10
1
3431-3434
2 (1–12 ) x dx x ∫ 8 2 ( ) ax bx c dx + + ∫ 9 (22 x) x e dx + ∫ 10 2 x –1 dx x       ∫ 11
1
3432-3435
2 ( ) ax bx c dx + + ∫ 9 (22 x) x e dx + ∫ 10 2 x –1 dx x       ∫ 11 3 2 2 5 4 x x – dx +x ∫ 12
1
3433-3436
(22 x) x e dx + ∫ 10 2 x –1 dx x       ∫ 11 3 2 2 5 4 x x – dx +x ∫ 12 3 3 4 x x dx x + + ∫ 13
1
3434-3437
2 x –1 dx x       ∫ 11 3 2 2 5 4 x x – dx +x ∫ 12 3 3 4 x x dx x + + ∫ 13 3 2 1 1 x x x – dx −x – + ∫ 14
1
3435-3438
3 2 2 5 4 x x – dx +x ∫ 12 3 3 4 x x dx x + + ∫ 13 3 2 1 1 x x x – dx −x – + ∫ 14 (1 – x) x dx ∫ 15
1
3436-3439
3 3 4 x x dx x + + ∫ 13 3 2 1 1 x x x – dx −x – + ∫ 14 (1 – x) x dx ∫ 15 ( 32 2 3) x x x dx + + ∫ 16
1
3437-3440
3 2 1 1 x x x – dx −x – + ∫ 14 (1 – x) x dx ∫ 15 ( 32 2 3) x x x dx + + ∫ 16 (2 3cos x) x – x e dx + ∫ 17
1
3438-3441
(1 – x) x dx ∫ 15 ( 32 2 3) x x x dx + + ∫ 16 (2 3cos x) x – x e dx + ∫ 17 (22 3sin 5 ) x – x x dx + ∫ 18
1
3439-3442
( 32 2 3) x x x dx + + ∫ 16 (2 3cos x) x – x e dx + ∫ 17 (22 3sin 5 ) x – x x dx + ∫ 18 sec (sec tan ) x x x dx + ∫ 19
1
3440-3443
(2 3cos x) x – x e dx + ∫ 17 (22 3sin 5 ) x – x x dx + ∫ 18 sec (sec tan ) x x x dx + ∫ 19 2 sec2 cosec x dx x ∫ 20
1
3441-3444
(22 3sin 5 ) x – x x dx + ∫ 18 sec (sec tan ) x x x dx + ∫ 19 2 sec2 cosec x dx x ∫ 20 2 2 – 3sin cos x x ∫ dx
1
3442-3445
sec (sec tan ) x x x dx + ∫ 19 2 sec2 cosec x dx x ∫ 20 2 2 – 3sin cos x x ∫ dx Choose the correct answer in Exercises 21 and 22
1
3443-3446
2 sec2 cosec x dx x ∫ 20 2 2 – 3sin cos x x ∫ dx Choose the correct answer in Exercises 21 and 22 21
1
3444-3447
2 2 – 3sin cos x x ∫ dx Choose the correct answer in Exercises 21 and 22 21 The anti derivative of 1 x x   +     equals (A) 1 1 3 2 1 2 C 3 x x + + (B) 2 2 23 1 C 3 2 x x + + (C) 3 1 2 2 2 2 C 3 x x + + (D) 3 1 2 2 3 1 C 2 2 x x + + 22
1
3445-3448
Choose the correct answer in Exercises 21 and 22 21 The anti derivative of 1 x x   +     equals (A) 1 1 3 2 1 2 C 3 x x + + (B) 2 2 23 1 C 3 2 x x + + (C) 3 1 2 2 2 2 C 3 x x + + (D) 3 1 2 2 3 1 C 2 2 x x + + 22 If 3 34 ( ) 4 d f x x dx x = − such that f (2) = 0
1
3446-3449
21 The anti derivative of 1 x x   +     equals (A) 1 1 3 2 1 2 C 3 x x + + (B) 2 2 23 1 C 3 2 x x + + (C) 3 1 2 2 2 2 C 3 x x + + (D) 3 1 2 2 3 1 C 2 2 x x + + 22 If 3 34 ( ) 4 d f x x dx x = − such that f (2) = 0 Then f (x) is (A) 4 13 129 8 x +x − (B) 3 14 129 8 x +x + (C) 4 13 129 8 x +x + (D) 3 14 129 8 x +x − 300 MATHEMATICS 7
1
3447-3450
The anti derivative of 1 x x   +     equals (A) 1 1 3 2 1 2 C 3 x x + + (B) 2 2 23 1 C 3 2 x x + + (C) 3 1 2 2 2 2 C 3 x x + + (D) 3 1 2 2 3 1 C 2 2 x x + + 22 If 3 34 ( ) 4 d f x x dx x = − such that f (2) = 0 Then f (x) is (A) 4 13 129 8 x +x − (B) 3 14 129 8 x +x + (C) 4 13 129 8 x +x + (D) 3 14 129 8 x +x − 300 MATHEMATICS 7 3 Methods of Integration In previous section, we discussed integrals of those functions which were readily obtainable from derivatives of some functions
1
3448-3451
If 3 34 ( ) 4 d f x x dx x = − such that f (2) = 0 Then f (x) is (A) 4 13 129 8 x +x − (B) 3 14 129 8 x +x + (C) 4 13 129 8 x +x + (D) 3 14 129 8 x +x − 300 MATHEMATICS 7 3 Methods of Integration In previous section, we discussed integrals of those functions which were readily obtainable from derivatives of some functions It was based on inspection, i
1
3449-3452
Then f (x) is (A) 4 13 129 8 x +x − (B) 3 14 129 8 x +x + (C) 4 13 129 8 x +x + (D) 3 14 129 8 x +x − 300 MATHEMATICS 7 3 Methods of Integration In previous section, we discussed integrals of those functions which were readily obtainable from derivatives of some functions It was based on inspection, i e
1
3450-3453
3 Methods of Integration In previous section, we discussed integrals of those functions which were readily obtainable from derivatives of some functions It was based on inspection, i e , on the search of a function F whose derivative is f which led us to the integral of f
1
3451-3454
It was based on inspection, i e , on the search of a function F whose derivative is f which led us to the integral of f However, this method, which depends on inspection, is not very suitable for many functions
1
3452-3455
e , on the search of a function F whose derivative is f which led us to the integral of f However, this method, which depends on inspection, is not very suitable for many functions Hence, we need to develop additional techniques or methods for finding the integrals by reducing them into standard forms
1
3453-3456
, on the search of a function F whose derivative is f which led us to the integral of f However, this method, which depends on inspection, is not very suitable for many functions Hence, we need to develop additional techniques or methods for finding the integrals by reducing them into standard forms Prominent among them are methods based on: 1
1
3454-3457
However, this method, which depends on inspection, is not very suitable for many functions Hence, we need to develop additional techniques or methods for finding the integrals by reducing them into standard forms Prominent among them are methods based on: 1 Integration by Substitution 2
1
3455-3458
Hence, we need to develop additional techniques or methods for finding the integrals by reducing them into standard forms Prominent among them are methods based on: 1 Integration by Substitution 2 Integration using Partial Fractions 3
1
3456-3459
Prominent among them are methods based on: 1 Integration by Substitution 2 Integration using Partial Fractions 3 Integration by Parts 7
1
3457-3460
Integration by Substitution 2 Integration using Partial Fractions 3 Integration by Parts 7 3
1
3458-3461
Integration using Partial Fractions 3 Integration by Parts 7 3 1 Integration by substitution In this section, we consider the method of integration by substitution
1
3459-3462
Integration by Parts 7 3 1 Integration by substitution In this section, we consider the method of integration by substitution The given integral ( ) ∫f x dx can be transformed into another form by changing the independent variable x to t by substituting x = g (t)
1
3460-3463
3 1 Integration by substitution In this section, we consider the method of integration by substitution The given integral ( ) ∫f x dx can be transformed into another form by changing the independent variable x to t by substituting x = g (t) Consider I = ( ) f x dx ∫ Put x = g(t) so that dx dt = g′(t)
1
3461-3464
1 Integration by substitution In this section, we consider the method of integration by substitution The given integral ( ) ∫f x dx can be transformed into another form by changing the independent variable x to t by substituting x = g (t) Consider I = ( ) f x dx ∫ Put x = g(t) so that dx dt = g′(t) We write dx = g′(t) dt Thus I = ( ) ( ( )) ( ) f x dx f g t g t dt = ′ ∫ ∫ This change of variable formula is one of the important tools available to us in the name of integration by substitution
1
3462-3465
The given integral ( ) ∫f x dx can be transformed into another form by changing the independent variable x to t by substituting x = g (t) Consider I = ( ) f x dx ∫ Put x = g(t) so that dx dt = g′(t) We write dx = g′(t) dt Thus I = ( ) ( ( )) ( ) f x dx f g t g t dt = ′ ∫ ∫ This change of variable formula is one of the important tools available to us in the name of integration by substitution It is often important to guess what will be the useful substitution
1
3463-3466
Consider I = ( ) f x dx ∫ Put x = g(t) so that dx dt = g′(t) We write dx = g′(t) dt Thus I = ( ) ( ( )) ( ) f x dx f g t g t dt = ′ ∫ ∫ This change of variable formula is one of the important tools available to us in the name of integration by substitution It is often important to guess what will be the useful substitution Usually, we make a substitution for a function whose derivative also occurs in the integrand as illustrated in the following examples
1
3464-3467
We write dx = g′(t) dt Thus I = ( ) ( ( )) ( ) f x dx f g t g t dt = ′ ∫ ∫ This change of variable formula is one of the important tools available to us in the name of integration by substitution It is often important to guess what will be the useful substitution Usually, we make a substitution for a function whose derivative also occurs in the integrand as illustrated in the following examples Example 5 Integrate the following functions w
1
3465-3468
It is often important to guess what will be the useful substitution Usually, we make a substitution for a function whose derivative also occurs in the integrand as illustrated in the following examples Example 5 Integrate the following functions w r
1
3466-3469
Usually, we make a substitution for a function whose derivative also occurs in the integrand as illustrated in the following examples Example 5 Integrate the following functions w r t
1
3467-3470
Example 5 Integrate the following functions w r t x: (i) sin mx (ii) 2x sin (x2 + 1) (iii) 4 2 tan xsec x x (iv) 1 2 sin (tan ) 1 x– x + Solution (i) We know that derivative of mx is m
1
3468-3471
r t x: (i) sin mx (ii) 2x sin (x2 + 1) (iii) 4 2 tan xsec x x (iv) 1 2 sin (tan ) 1 x– x + Solution (i) We know that derivative of mx is m Thus, we make the substitution mx = t so that mdx = dt
1
3469-3472
t x: (i) sin mx (ii) 2x sin (x2 + 1) (iii) 4 2 tan xsec x x (iv) 1 2 sin (tan ) 1 x– x + Solution (i) We know that derivative of mx is m Thus, we make the substitution mx = t so that mdx = dt Therefore, 1 sin sin mx dx t dt m = ∫ ∫ = – 1 m cos t + C = – 1 m cos mx + C INTEGRALS 301 (ii) Derivative of x2 + 1 is 2x
1
3470-3473
x: (i) sin mx (ii) 2x sin (x2 + 1) (iii) 4 2 tan xsec x x (iv) 1 2 sin (tan ) 1 x– x + Solution (i) We know that derivative of mx is m Thus, we make the substitution mx = t so that mdx = dt Therefore, 1 sin sin mx dx t dt m = ∫ ∫ = – 1 m cos t + C = – 1 m cos mx + C INTEGRALS 301 (ii) Derivative of x2 + 1 is 2x Thus, we use the substitution x2 + 1 = t so that 2x dx = dt
1
3471-3474
Thus, we make the substitution mx = t so that mdx = dt Therefore, 1 sin sin mx dx t dt m = ∫ ∫ = – 1 m cos t + C = – 1 m cos mx + C INTEGRALS 301 (ii) Derivative of x2 + 1 is 2x Thus, we use the substitution x2 + 1 = t so that 2x dx = dt Therefore, 2 sin (2 1) sin x x dx t dt + = ∫ ∫ = – cos t + C = – cos (x2 + 1) + C (iii) Derivative of x is 21 1 1 2 2 – x x =
1
3472-3475
Therefore, 1 sin sin mx dx t dt m = ∫ ∫ = – 1 m cos t + C = – 1 m cos mx + C INTEGRALS 301 (ii) Derivative of x2 + 1 is 2x Thus, we use the substitution x2 + 1 = t so that 2x dx = dt Therefore, 2 sin (2 1) sin x x dx t dt + = ∫ ∫ = – cos t + C = – cos (x2 + 1) + C (iii) Derivative of x is 21 1 1 2 2 – x x = Thus, we use the substitution 1 so that giving 2 x t dx dt x = = dx = 2t dt
1
3473-3476
Thus, we use the substitution x2 + 1 = t so that 2x dx = dt Therefore, 2 sin (2 1) sin x x dx t dt + = ∫ ∫ = – cos t + C = – cos (x2 + 1) + C (iii) Derivative of x is 21 1 1 2 2 – x x = Thus, we use the substitution 1 so that giving 2 x t dx dt x = = dx = 2t dt Thus, 4 2 4 2 tan sec 2 tan sec x x t t t dt dx t x = ∫ ∫ = 4 2 2 tan tsec t dt ∫ Again, we make another substitution tan t = u so that sec2 t dt = du Therefore, 4 2 4 2 tan sec 2 t t dt u du = ∫ ∫ = 5 2 C 5 u + = 2 tan5 C 5 t + (since u = tan t) = 2 tan5 C (since ) 5 x t x + = Hence, 4 2 tan xsec x dx x ∫ = 2 tan5 C 5 x + Alternatively, make the substitution tan x t = (iv) Derivative of 1 2 1 tan 1 – x x = +
1
3474-3477
Therefore, 2 sin (2 1) sin x x dx t dt + = ∫ ∫ = – cos t + C = – cos (x2 + 1) + C (iii) Derivative of x is 21 1 1 2 2 – x x = Thus, we use the substitution 1 so that giving 2 x t dx dt x = = dx = 2t dt Thus, 4 2 4 2 tan sec 2 tan sec x x t t t dt dx t x = ∫ ∫ = 4 2 2 tan tsec t dt ∫ Again, we make another substitution tan t = u so that sec2 t dt = du Therefore, 4 2 4 2 tan sec 2 t t dt u du = ∫ ∫ = 5 2 C 5 u + = 2 tan5 C 5 t + (since u = tan t) = 2 tan5 C (since ) 5 x t x + = Hence, 4 2 tan xsec x dx x ∫ = 2 tan5 C 5 x + Alternatively, make the substitution tan x t = (iv) Derivative of 1 2 1 tan 1 – x x = + Thus, we use the substitution tan–1 x = t so that 2 1 dx x + = dt
1
3475-3478
Thus, we use the substitution 1 so that giving 2 x t dx dt x = = dx = 2t dt Thus, 4 2 4 2 tan sec 2 tan sec x x t t t dt dx t x = ∫ ∫ = 4 2 2 tan tsec t dt ∫ Again, we make another substitution tan t = u so that sec2 t dt = du Therefore, 4 2 4 2 tan sec 2 t t dt u du = ∫ ∫ = 5 2 C 5 u + = 2 tan5 C 5 t + (since u = tan t) = 2 tan5 C (since ) 5 x t x + = Hence, 4 2 tan xsec x dx x ∫ = 2 tan5 C 5 x + Alternatively, make the substitution tan x t = (iv) Derivative of 1 2 1 tan 1 – x x = + Thus, we use the substitution tan–1 x = t so that 2 1 dx x + = dt Therefore , 1 sin (tan2 ) sin 1 – x dx t dt x = + ∫ ∫ = – cos t + C = – cos (tan –1x) + C Now, we discuss some important integrals involving trigonometric functions and their standard integrals using substitution technique
1
3476-3479
Thus, 4 2 4 2 tan sec 2 tan sec x x t t t dt dx t x = ∫ ∫ = 4 2 2 tan tsec t dt ∫ Again, we make another substitution tan t = u so that sec2 t dt = du Therefore, 4 2 4 2 tan sec 2 t t dt u du = ∫ ∫ = 5 2 C 5 u + = 2 tan5 C 5 t + (since u = tan t) = 2 tan5 C (since ) 5 x t x + = Hence, 4 2 tan xsec x dx x ∫ = 2 tan5 C 5 x + Alternatively, make the substitution tan x t = (iv) Derivative of 1 2 1 tan 1 – x x = + Thus, we use the substitution tan–1 x = t so that 2 1 dx x + = dt Therefore , 1 sin (tan2 ) sin 1 – x dx t dt x = + ∫ ∫ = – cos t + C = – cos (tan –1x) + C Now, we discuss some important integrals involving trigonometric functions and their standard integrals using substitution technique These will be used later without reference
1
3477-3480
Thus, we use the substitution tan–1 x = t so that 2 1 dx x + = dt Therefore , 1 sin (tan2 ) sin 1 – x dx t dt x = + ∫ ∫ = – cos t + C = – cos (tan –1x) + C Now, we discuss some important integrals involving trigonometric functions and their standard integrals using substitution technique These will be used later without reference (i) ∫tan = log sec + C x dx x We have sin tan cos x x dx dx x = ∫ ∫ 302 MATHEMATICS Put cos x = t so that sin x dx = – dt Then tan log C log cos C dt x dx – – t – x t = = + = + ∫ ∫ or tan log sec C x dx x = + ∫ (ii) ∫cot = log sin + C x dx x We have cos cot sin x x dx dx x = ∫ ∫ Put sin x = t so that cos x dx = dt Then cot dt x dx t = ∫ ∫ = log t +C = log sin C x + (iii) ∫sec = log sec + tan + C x dx x x We have sec (sec tan ) sec sec + tan x x x x dx dx x +x = ∫ ∫ Put sec x + tan x = t so that sec x (tan x + sec x) dx = dt Therefore, sec log + C = log sec tan C dt x dx t x x t = = + + ∫ ∫ (iv) ∫cosec = log cosec – cot + C x dx x x We have cosec (cosec cot ) cosec (cosec cot ) x x x x dx dx x +x = + ∫ ∫ Put cosec x + cot x = t so that – cosec x (cosec x + cot x) dx = dt So cosec – –log| | – log|cosec cot | C dt x dx t x x t = = = + + ∫ ∫ = 2 2 cosec cot – log C cosec cot x x x x − + − = log cosec cot C x – x + Example 6 Find the following integrals: (i) 3 2 sin xcos x dx ∫ (ii) sin sin ( ) x dx x +a ∫ (iii) 1 1 tan dx x ∫+ INTEGRALS 303 Solution (i) We have 3 2 2 2 sin cos sin cos (sin ) x x dx x x x dx = ∫ ∫ = 2 2 (1– cos ) cos (sin ) x x x dx ∫ Put t = cos x so that dt = – sin x dx Therefore, 2 2 sin cos (sin ) x x x dx ∫ = 2 2 (1– t) t dt −∫ = 3 5 2 4 ( – ) C 3 5 t t – t t dt – –   = +     ∫ = 3 5 1 1 cos cos C 3 5 – x x + + (ii) Put x + a = t
1
3478-3481
Therefore , 1 sin (tan2 ) sin 1 – x dx t dt x = + ∫ ∫ = – cos t + C = – cos (tan –1x) + C Now, we discuss some important integrals involving trigonometric functions and their standard integrals using substitution technique These will be used later without reference (i) ∫tan = log sec + C x dx x We have sin tan cos x x dx dx x = ∫ ∫ 302 MATHEMATICS Put cos x = t so that sin x dx = – dt Then tan log C log cos C dt x dx – – t – x t = = + = + ∫ ∫ or tan log sec C x dx x = + ∫ (ii) ∫cot = log sin + C x dx x We have cos cot sin x x dx dx x = ∫ ∫ Put sin x = t so that cos x dx = dt Then cot dt x dx t = ∫ ∫ = log t +C = log sin C x + (iii) ∫sec = log sec + tan + C x dx x x We have sec (sec tan ) sec sec + tan x x x x dx dx x +x = ∫ ∫ Put sec x + tan x = t so that sec x (tan x + sec x) dx = dt Therefore, sec log + C = log sec tan C dt x dx t x x t = = + + ∫ ∫ (iv) ∫cosec = log cosec – cot + C x dx x x We have cosec (cosec cot ) cosec (cosec cot ) x x x x dx dx x +x = + ∫ ∫ Put cosec x + cot x = t so that – cosec x (cosec x + cot x) dx = dt So cosec – –log| | – log|cosec cot | C dt x dx t x x t = = = + + ∫ ∫ = 2 2 cosec cot – log C cosec cot x x x x − + − = log cosec cot C x – x + Example 6 Find the following integrals: (i) 3 2 sin xcos x dx ∫ (ii) sin sin ( ) x dx x +a ∫ (iii) 1 1 tan dx x ∫+ INTEGRALS 303 Solution (i) We have 3 2 2 2 sin cos sin cos (sin ) x x dx x x x dx = ∫ ∫ = 2 2 (1– cos ) cos (sin ) x x x dx ∫ Put t = cos x so that dt = – sin x dx Therefore, 2 2 sin cos (sin ) x x x dx ∫ = 2 2 (1– t) t dt −∫ = 3 5 2 4 ( – ) C 3 5 t t – t t dt – –   = +     ∫ = 3 5 1 1 cos cos C 3 5 – x x + + (ii) Put x + a = t Then dx = dt
1
3479-3482
These will be used later without reference (i) ∫tan = log sec + C x dx x We have sin tan cos x x dx dx x = ∫ ∫ 302 MATHEMATICS Put cos x = t so that sin x dx = – dt Then tan log C log cos C dt x dx – – t – x t = = + = + ∫ ∫ or tan log sec C x dx x = + ∫ (ii) ∫cot = log sin + C x dx x We have cos cot sin x x dx dx x = ∫ ∫ Put sin x = t so that cos x dx = dt Then cot dt x dx t = ∫ ∫ = log t +C = log sin C x + (iii) ∫sec = log sec + tan + C x dx x x We have sec (sec tan ) sec sec + tan x x x x dx dx x +x = ∫ ∫ Put sec x + tan x = t so that sec x (tan x + sec x) dx = dt Therefore, sec log + C = log sec tan C dt x dx t x x t = = + + ∫ ∫ (iv) ∫cosec = log cosec – cot + C x dx x x We have cosec (cosec cot ) cosec (cosec cot ) x x x x dx dx x +x = + ∫ ∫ Put cosec x + cot x = t so that – cosec x (cosec x + cot x) dx = dt So cosec – –log| | – log|cosec cot | C dt x dx t x x t = = = + + ∫ ∫ = 2 2 cosec cot – log C cosec cot x x x x − + − = log cosec cot C x – x + Example 6 Find the following integrals: (i) 3 2 sin xcos x dx ∫ (ii) sin sin ( ) x dx x +a ∫ (iii) 1 1 tan dx x ∫+ INTEGRALS 303 Solution (i) We have 3 2 2 2 sin cos sin cos (sin ) x x dx x x x dx = ∫ ∫ = 2 2 (1– cos ) cos (sin ) x x x dx ∫ Put t = cos x so that dt = – sin x dx Therefore, 2 2 sin cos (sin ) x x x dx ∫ = 2 2 (1– t) t dt −∫ = 3 5 2 4 ( – ) C 3 5 t t – t t dt – –   = +     ∫ = 3 5 1 1 cos cos C 3 5 – x x + + (ii) Put x + a = t Then dx = dt Therefore sin sin ( ) sin ( ) sin x t – a dx dt x a t = + ∫ ∫ = sin cos cos sin sin t a – t a dt t ∫ = cos – sin cot a dt a t dt ∫ ∫ = 1 (cos ) (sin ) log sin C a t – a t   +   = 1 (cos ) ( ) (sin ) log sin ( ) C a x a – a x a   + + +   = 1 cos cos (sin ) log sin ( ) C sin x a a a – a x a – a + + Hence, sin sin ( ) x dx x +a ∫ = x cos a – sin a log |sin (x + a)| + C, where, C = – C1 sin a + a cos a, is another arbitrary constant
1
3480-3483
(i) ∫tan = log sec + C x dx x We have sin tan cos x x dx dx x = ∫ ∫ 302 MATHEMATICS Put cos x = t so that sin x dx = – dt Then tan log C log cos C dt x dx – – t – x t = = + = + ∫ ∫ or tan log sec C x dx x = + ∫ (ii) ∫cot = log sin + C x dx x We have cos cot sin x x dx dx x = ∫ ∫ Put sin x = t so that cos x dx = dt Then cot dt x dx t = ∫ ∫ = log t +C = log sin C x + (iii) ∫sec = log sec + tan + C x dx x x We have sec (sec tan ) sec sec + tan x x x x dx dx x +x = ∫ ∫ Put sec x + tan x = t so that sec x (tan x + sec x) dx = dt Therefore, sec log + C = log sec tan C dt x dx t x x t = = + + ∫ ∫ (iv) ∫cosec = log cosec – cot + C x dx x x We have cosec (cosec cot ) cosec (cosec cot ) x x x x dx dx x +x = + ∫ ∫ Put cosec x + cot x = t so that – cosec x (cosec x + cot x) dx = dt So cosec – –log| | – log|cosec cot | C dt x dx t x x t = = = + + ∫ ∫ = 2 2 cosec cot – log C cosec cot x x x x − + − = log cosec cot C x – x + Example 6 Find the following integrals: (i) 3 2 sin xcos x dx ∫ (ii) sin sin ( ) x dx x +a ∫ (iii) 1 1 tan dx x ∫+ INTEGRALS 303 Solution (i) We have 3 2 2 2 sin cos sin cos (sin ) x x dx x x x dx = ∫ ∫ = 2 2 (1– cos ) cos (sin ) x x x dx ∫ Put t = cos x so that dt = – sin x dx Therefore, 2 2 sin cos (sin ) x x x dx ∫ = 2 2 (1– t) t dt −∫ = 3 5 2 4 ( – ) C 3 5 t t – t t dt – –   = +     ∫ = 3 5 1 1 cos cos C 3 5 – x x + + (ii) Put x + a = t Then dx = dt Therefore sin sin ( ) sin ( ) sin x t – a dx dt x a t = + ∫ ∫ = sin cos cos sin sin t a – t a dt t ∫ = cos – sin cot a dt a t dt ∫ ∫ = 1 (cos ) (sin ) log sin C a t – a t   +   = 1 (cos ) ( ) (sin ) log sin ( ) C a x a – a x a   + + +   = 1 cos cos (sin ) log sin ( ) C sin x a a a – a x a – a + + Hence, sin sin ( ) x dx x +a ∫ = x cos a – sin a log |sin (x + a)| + C, where, C = – C1 sin a + a cos a, is another arbitrary constant (iii) cos 1 tan cos sin dx x dx x x x = + + ∫ ∫ = 1 (cos + sin + cos – sin ) 2 cos sin x x x x dx x x + ∫ 304 MATHEMATICS = 1 1 cos – sin 2 2 cos sin x x dx dx x x + + ∫ ∫ = C1 1 cos sin 2 2 2 cos sin x x – x dx x x + + + ∫
1
3481-3484
Then dx = dt Therefore sin sin ( ) sin ( ) sin x t – a dx dt x a t = + ∫ ∫ = sin cos cos sin sin t a – t a dt t ∫ = cos – sin cot a dt a t dt ∫ ∫ = 1 (cos ) (sin ) log sin C a t – a t   +   = 1 (cos ) ( ) (sin ) log sin ( ) C a x a – a x a   + + +   = 1 cos cos (sin ) log sin ( ) C sin x a a a – a x a – a + + Hence, sin sin ( ) x dx x +a ∫ = x cos a – sin a log |sin (x + a)| + C, where, C = – C1 sin a + a cos a, is another arbitrary constant (iii) cos 1 tan cos sin dx x dx x x x = + + ∫ ∫ = 1 (cos + sin + cos – sin ) 2 cos sin x x x x dx x x + ∫ 304 MATHEMATICS = 1 1 cos – sin 2 2 cos sin x x dx dx x x + + ∫ ∫ = C1 1 cos sin 2 2 2 cos sin x x – x dx x x + + + ∫ (1) Now, consider cos sin I cos sin x – x dx x x = + ∫ Put cos x + sin x = t so that (cos x – sin x) dx = dt Therefore 2 I log C dt t t = = + ∫ = 2 log cos sin C x x + + Putting it in (1), we get 1 2 C C 1 + + log cos sin 1 tan 2 2 2 2 dx x x x x = + + + ∫ = 1 2 C C +1 log cos sin 2 2 2 2 x x x + + + = 1 2 C C +1 log cos sin C C 2 2 2 2 x x x ,  + + = +     EXERCISE 7
1
3482-3485
Therefore sin sin ( ) sin ( ) sin x t – a dx dt x a t = + ∫ ∫ = sin cos cos sin sin t a – t a dt t ∫ = cos – sin cot a dt a t dt ∫ ∫ = 1 (cos ) (sin ) log sin C a t – a t   +   = 1 (cos ) ( ) (sin ) log sin ( ) C a x a – a x a   + + +   = 1 cos cos (sin ) log sin ( ) C sin x a a a – a x a – a + + Hence, sin sin ( ) x dx x +a ∫ = x cos a – sin a log |sin (x + a)| + C, where, C = – C1 sin a + a cos a, is another arbitrary constant (iii) cos 1 tan cos sin dx x dx x x x = + + ∫ ∫ = 1 (cos + sin + cos – sin ) 2 cos sin x x x x dx x x + ∫ 304 MATHEMATICS = 1 1 cos – sin 2 2 cos sin x x dx dx x x + + ∫ ∫ = C1 1 cos sin 2 2 2 cos sin x x – x dx x x + + + ∫ (1) Now, consider cos sin I cos sin x – x dx x x = + ∫ Put cos x + sin x = t so that (cos x – sin x) dx = dt Therefore 2 I log C dt t t = = + ∫ = 2 log cos sin C x x + + Putting it in (1), we get 1 2 C C 1 + + log cos sin 1 tan 2 2 2 2 dx x x x x = + + + ∫ = 1 2 C C +1 log cos sin 2 2 2 2 x x x + + + = 1 2 C C +1 log cos sin C C 2 2 2 2 x x x ,  + + = +     EXERCISE 7 2 Integrate the functions in Exercises 1 to 37: 1
1
3483-3486
(iii) cos 1 tan cos sin dx x dx x x x = + + ∫ ∫ = 1 (cos + sin + cos – sin ) 2 cos sin x x x x dx x x + ∫ 304 MATHEMATICS = 1 1 cos – sin 2 2 cos sin x x dx dx x x + + ∫ ∫ = C1 1 cos sin 2 2 2 cos sin x x – x dx x x + + + ∫ (1) Now, consider cos sin I cos sin x – x dx x x = + ∫ Put cos x + sin x = t so that (cos x – sin x) dx = dt Therefore 2 I log C dt t t = = + ∫ = 2 log cos sin C x x + + Putting it in (1), we get 1 2 C C 1 + + log cos sin 1 tan 2 2 2 2 dx x x x x = + + + ∫ = 1 2 C C +1 log cos sin 2 2 2 2 x x x + + + = 1 2 C C +1 log cos sin C C 2 2 2 2 x x x ,  + + = +     EXERCISE 7 2 Integrate the functions in Exercises 1 to 37: 1 2 2 1 +xx 2
1
3484-3487
(1) Now, consider cos sin I cos sin x – x dx x x = + ∫ Put cos x + sin x = t so that (cos x – sin x) dx = dt Therefore 2 I log C dt t t = = + ∫ = 2 log cos sin C x x + + Putting it in (1), we get 1 2 C C 1 + + log cos sin 1 tan 2 2 2 2 dx x x x x = + + + ∫ = 1 2 C C +1 log cos sin 2 2 2 2 x x x + + + = 1 2 C C +1 log cos sin C C 2 2 2 2 x x x ,  + + = +     EXERCISE 7 2 Integrate the functions in Exercises 1 to 37: 1 2 2 1 +xx 2 ( ) 2 log x x 3
1
3485-3488
2 Integrate the functions in Exercises 1 to 37: 1 2 2 1 +xx 2 ( ) 2 log x x 3 1 log x x x + 4
1
3486-3489
2 2 1 +xx 2 ( ) 2 log x x 3 1 log x x x + 4 sin xsin (cos ) x 5
1
3487-3490
( ) 2 log x x 3 1 log x x x + 4 sin xsin (cos ) x 5 sin ( ) cos ( ) ax b ax b + + 6
1
3488-3491
1 log x x x + 4 sin xsin (cos ) x 5 sin ( ) cos ( ) ax b ax b + + 6 ax +b 7
1
3489-3492
sin xsin (cos ) x 5 sin ( ) cos ( ) ax b ax b + + 6 ax +b 7 2 x x + 8
1
3490-3493
sin ( ) cos ( ) ax b ax b + + 6 ax +b 7 2 x x + 8 2 1 2 x x + 9
1
3491-3494
ax +b 7 2 x x + 8 2 1 2 x x + 9 2 (4 2) 1 x x x + + + 10
1
3492-3495
2 x x + 8 2 1 2 x x + 9 2 (4 2) 1 x x x + + + 10 1 x – x 11
1
3493-3496
2 1 2 x x + 9 2 (4 2) 1 x x x + + + 10 1 x – x 11 4 x x + , x > 0 12
1
3494-3497
2 (4 2) 1 x x x + + + 10 1 x – x 11 4 x x + , x > 0 12 1 3 5 3 ( x –1) x 13
1
3495-3498
1 x – x 11 4 x x + , x > 0 12 1 3 5 3 ( x –1) x 13 2 3 3 (2 3 ) x +x 14
1
3496-3499
4 x x + , x > 0 12 1 3 5 3 ( x –1) x 13 2 3 3 (2 3 ) x +x 14 1 x(log )m x , x > 0, ≠1 m 15
1
3497-3500
1 3 5 3 ( x –1) x 13 2 3 3 (2 3 ) x +x 14 1 x(log )m x , x > 0, ≠1 m 15 2 9 4 x – x 16
1
3498-3501
2 3 3 (2 3 ) x +x 14 1 x(log )m x , x > 0, ≠1 m 15 2 9 4 x – x 16 2 3 ex + 17
1
3499-3502
1 x(log )m x , x > 0, ≠1 m 15 2 9 4 x – x 16 2 3 ex + 17 x2 x e INTEGRALS 305 18
1
3500-3503
2 9 4 x – x 16 2 3 ex + 17 x2 x e INTEGRALS 305 18 1 2 1 tan– x e +x 19
1
3501-3504
2 3 ex + 17 x2 x e INTEGRALS 305 18 1 2 1 tan– x e +x 19 2 2 1 1 x x e – e + 20
1
3502-3505
x2 x e INTEGRALS 305 18 1 2 1 tan– x e +x 19 2 2 1 1 x x e – e + 20 2 2 2 2 x – x x – x e – e e e + 21
1
3503-3506
1 2 1 tan– x e +x 19 2 2 1 1 x x e – e + 20 2 2 2 2 x – x x – x e – e e e + 21 tan2 (2x – 3) 22
1
3504-3507
2 2 1 1 x x e – e + 20 2 2 2 2 x – x x – x e – e e e + 21 tan2 (2x – 3) 22 sec2 (7 – 4x) 23
1
3505-3508
2 2 2 2 x – x x – x e – e e e + 21 tan2 (2x – 3) 22 sec2 (7 – 4x) 23 1 2 sin 1 – x – x 24
1
3506-3509
tan2 (2x – 3) 22 sec2 (7 – 4x) 23 1 2 sin 1 – x – x 24 2cos 3sin 6cos 4sin x – x x x + 25
1
3507-3510
sec2 (7 – 4x) 23 1 2 sin 1 – x – x 24 2cos 3sin 6cos 4sin x – x x x + 25 2 2 1 cos (1 tan ) x – x 26
1
3508-3511
1 2 sin 1 – x – x 24 2cos 3sin 6cos 4sin x – x x x + 25 2 2 1 cos (1 tan ) x – x 26 cos x x 27
1
3509-3512
2cos 3sin 6cos 4sin x – x x x + 25 2 2 1 cos (1 tan ) x – x 26 cos x x 27 sin 2 cos 2 x x 28
1
3510-3513
2 2 1 cos (1 tan ) x – x 26 cos x x 27 sin 2 cos 2 x x 28 cos 1 sin x x + 29
1
3511-3514
cos x x 27 sin 2 cos 2 x x 28 cos 1 sin x x + 29 cot x log sin x 30
1
3512-3515
sin 2 cos 2 x x 28 cos 1 sin x x + 29 cot x log sin x 30 sin 1 cos x x + 31
1
3513-3516
cos 1 sin x x + 29 cot x log sin x 30 sin 1 cos x x + 31 ( ) 2 sin 1 cos x x + 32
1
3514-3517
cot x log sin x 30 sin 1 cos x x + 31 ( ) 2 sin 1 cos x x + 32 1 1 cot x + 33
1
3515-3518
sin 1 cos x x + 31 ( ) 2 sin 1 cos x x + 32 1 1 cot x + 33 1 1 –tan x 34
1
3516-3519
( ) 2 sin 1 cos x x + 32 1 1 cot x + 33 1 1 –tan x 34 tan sin cos x x x 35
1
3517-3520
1 1 cot x + 33 1 1 –tan x 34 tan sin cos x x x 35 ( ) 2 1 log x x + 36