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, ( 2) 12 1 1 x y − = So 2 2 1 2 1 (1 ) 2 (0 2 ) 0 x y y y x − + − = Hence (1 – x2) y2 – xy1 = 0 EXERCISE 5 7 Find the second order derivatives of the functions given in Exercises 1 to 10 1
1
2419-2422
2 (0 2 ) 0 x y y y x − + − = Hence (1 – x2) y2 – xy1 = 0 EXERCISE 5 7 Find the second order derivatives of the functions given in Exercises 1 to 10 1 x2 + 3x + 2 2
1
2420-2423
7 Find the second order derivatives of the functions given in Exercises 1 to 10 1 x2 + 3x + 2 2 x20 3
1
2421-2424
1 x2 + 3x + 2 2 x20 3 x
1
2422-2425
x2 + 3x + 2 2 x20 3 x cos x 4
1
2423-2426
x20 3 x cos x 4 log x 5
1
2424-2427
x cos x 4 log x 5 x3 log x 6
1
2425-2428
cos x 4 log x 5 x3 log x 6 ex sin 5x 7
1
2426-2429
log x 5 x3 log x 6 ex sin 5x 7 e6x cos 3x 8
1
2427-2430
x3 log x 6 ex sin 5x 7 e6x cos 3x 8 tan–1 x 9
1
2428-2431
ex sin 5x 7 e6x cos 3x 8 tan–1 x 9 log (log x) 10
1
2429-2432
e6x cos 3x 8 tan–1 x 9 log (log x) 10 sin (log x) 11
1
2430-2433
tan–1 x 9 log (log x) 10 sin (log x) 11 If y = 5 cos x – 3 sin x, prove that 2 2 0 d y y dx + = Rationalised 2023-24 MATHEMATICS 140 12
1
2431-2434
log (log x) 10 sin (log x) 11 If y = 5 cos x – 3 sin x, prove that 2 2 0 d y y dx + = Rationalised 2023-24 MATHEMATICS 140 12 If y = cos–1 x, Find 2 2 d y dx in terms of y alone
1
2432-2435
sin (log x) 11 If y = 5 cos x – 3 sin x, prove that 2 2 0 d y y dx + = Rationalised 2023-24 MATHEMATICS 140 12 If y = cos–1 x, Find 2 2 d y dx in terms of y alone 13
1
2433-2436
If y = 5 cos x – 3 sin x, prove that 2 2 0 d y y dx + = Rationalised 2023-24 MATHEMATICS 140 12 If y = cos–1 x, Find 2 2 d y dx in terms of y alone 13 If y = 3 cos (log x) + 4 sin (log x), show that x2 y2 + xy1 + y = 0 14
1
2434-2437
If y = cos–1 x, Find 2 2 d y dx in terms of y alone 13 If y = 3 cos (log x) + 4 sin (log x), show that x2 y2 + xy1 + y = 0 14 If y = Aemx + Benx, show that 2 2 ( ) 0 d y dy m n mny dx dx − + + = 15
1
2435-2438
13 If y = 3 cos (log x) + 4 sin (log x), show that x2 y2 + xy1 + y = 0 14 If y = Aemx + Benx, show that 2 2 ( ) 0 d y dy m n mny dx dx − + + = 15 If y = 500e7x + 600e–7x, show that 2 2 49 d y y dx = 16
1
2436-2439
If y = 3 cos (log x) + 4 sin (log x), show that x2 y2 + xy1 + y = 0 14 If y = Aemx + Benx, show that 2 2 ( ) 0 d y dy m n mny dx dx − + + = 15 If y = 500e7x + 600e–7x, show that 2 2 49 d y y dx = 16 If ey (x + 1) = 1, show that 2 2 2 d y dy dx dx   =     17
1
2437-2440
If y = Aemx + Benx, show that 2 2 ( ) 0 d y dy m n mny dx dx − + + = 15 If y = 500e7x + 600e–7x, show that 2 2 49 d y y dx = 16 If ey (x + 1) = 1, show that 2 2 2 d y dy dx dx   =     17 If y = (tan–1 x)2, show that (x2 + 1)2 y2 + 2x (x2 + 1) y1 = 2 Miscellaneous Examples Example 39 Differentiate w
1
2438-2441
If y = 500e7x + 600e–7x, show that 2 2 49 d y y dx = 16 If ey (x + 1) = 1, show that 2 2 2 d y dy dx dx   =     17 If y = (tan–1 x)2, show that (x2 + 1)2 y2 + 2x (x2 + 1) y1 = 2 Miscellaneous Examples Example 39 Differentiate w r
1
2439-2442
If ey (x + 1) = 1, show that 2 2 2 d y dy dx dx   =     17 If y = (tan–1 x)2, show that (x2 + 1)2 y2 + 2x (x2 + 1) y1 = 2 Miscellaneous Examples Example 39 Differentiate w r t
1
2440-2443
If y = (tan–1 x)2, show that (x2 + 1)2 y2 + 2x (x2 + 1) y1 = 2 Miscellaneous Examples Example 39 Differentiate w r t x, the following function: (i) 12 3 2 2 4 x x + + + (ii) log7 (log x) Solution (i) Let y = 12 3 2 2 4 x x + + + = 1 1 2 2 2 (3 2) (2 4) x x − + + + Note that this function is defined at all real numbers x > −32
1
2441-2444
r t x, the following function: (i) 12 3 2 2 4 x x + + + (ii) log7 (log x) Solution (i) Let y = 12 3 2 2 4 x x + + + = 1 1 2 2 2 (3 2) (2 4) x x − + + + Note that this function is defined at all real numbers x > −32 Therefore dy dx = 1 1 1 1 2 2 2 2 1 1 (3 2) (3 2) (2 4) (2 4) 2 2 d d x x x x dx dx − − −   + ⋅ + + − + ⋅ +     = 1 2 3 2 3 21 2 4 4 21 2 23 ( ) ( ) ( ) x x x + ⋅ −     + ⋅ − − = ( ) 3 2 2 3 2 2 3 2 2 4 x x x − + + This is defined for all real numbers x > −32
1
2442-2445
t x, the following function: (i) 12 3 2 2 4 x x + + + (ii) log7 (log x) Solution (i) Let y = 12 3 2 2 4 x x + + + = 1 1 2 2 2 (3 2) (2 4) x x − + + + Note that this function is defined at all real numbers x > −32 Therefore dy dx = 1 1 1 1 2 2 2 2 1 1 (3 2) (3 2) (2 4) (2 4) 2 2 d d x x x x dx dx − − −   + ⋅ + + − + ⋅ +     = 1 2 3 2 3 21 2 4 4 21 2 23 ( ) ( ) ( ) x x x + ⋅ −     + ⋅ − − = ( ) 3 2 2 3 2 2 3 2 2 4 x x x − + + This is defined for all real numbers x > −32 Rationalised 2023-24 CONTINUITY AND DIFFERENTIABILITY 141 (ii) Let y = log7 (log x) = log (log ) log7 x (by change of base formula)
1
2443-2446
x, the following function: (i) 12 3 2 2 4 x x + + + (ii) log7 (log x) Solution (i) Let y = 12 3 2 2 4 x x + + + = 1 1 2 2 2 (3 2) (2 4) x x − + + + Note that this function is defined at all real numbers x > −32 Therefore dy dx = 1 1 1 1 2 2 2 2 1 1 (3 2) (3 2) (2 4) (2 4) 2 2 d d x x x x dx dx − − −   + ⋅ + + − + ⋅ +     = 1 2 3 2 3 21 2 4 4 21 2 23 ( ) ( ) ( ) x x x + ⋅ −     + ⋅ − − = ( ) 3 2 2 3 2 2 3 2 2 4 x x x − + + This is defined for all real numbers x > −32 Rationalised 2023-24 CONTINUITY AND DIFFERENTIABILITY 141 (ii) Let y = log7 (log x) = log (log ) log7 x (by change of base formula) The function is defined for all real numbers x > 1
1
2444-2447
Therefore dy dx = 1 1 1 1 2 2 2 2 1 1 (3 2) (3 2) (2 4) (2 4) 2 2 d d x x x x dx dx − − −   + ⋅ + + − + ⋅ +     = 1 2 3 2 3 21 2 4 4 21 2 23 ( ) ( ) ( ) x x x + ⋅ −     + ⋅ − − = ( ) 3 2 2 3 2 2 3 2 2 4 x x x − + + This is defined for all real numbers x > −32 Rationalised 2023-24 CONTINUITY AND DIFFERENTIABILITY 141 (ii) Let y = log7 (log x) = log (log ) log7 x (by change of base formula) The function is defined for all real numbers x > 1 Therefore dy dx = 1 (log (log )) log7 d x dx = 1 1 (log ) log7 log d x x dx ⋅ = 1 xlog7 log x Example 40 Differentiate the following w
1
2445-2448
Rationalised 2023-24 CONTINUITY AND DIFFERENTIABILITY 141 (ii) Let y = log7 (log x) = log (log ) log7 x (by change of base formula) The function is defined for all real numbers x > 1 Therefore dy dx = 1 (log (log )) log7 d x dx = 1 1 (log ) log7 log d x x dx ⋅ = 1 xlog7 log x Example 40 Differentiate the following w r
1
2446-2449
The function is defined for all real numbers x > 1 Therefore dy dx = 1 (log (log )) log7 d x dx = 1 1 (log ) log7 log d x x dx ⋅ = 1 xlog7 log x Example 40 Differentiate the following w r t
1
2447-2450
Therefore dy dx = 1 (log (log )) log7 d x dx = 1 1 (log ) log7 log d x x dx ⋅ = 1 xlog7 log x Example 40 Differentiate the following w r t x
1
2448-2451
r t x (i) cos –1 (sin x) (ii) 1 sin tan 1 cos x x −     +  (iii) 1 1 2 sin 1 4 x x + −     +  Solution (i) Let f (x) = cos –1 (sin x)
1
2449-2452
t x (i) cos –1 (sin x) (ii) 1 sin tan 1 cos x x −     +  (iii) 1 1 2 sin 1 4 x x + −     +  Solution (i) Let f (x) = cos –1 (sin x) Observe that this function is defined for all real numbers
1
2450-2453
x (i) cos –1 (sin x) (ii) 1 sin tan 1 cos x x −     +  (iii) 1 1 2 sin 1 4 x x + −     +  Solution (i) Let f (x) = cos –1 (sin x) Observe that this function is defined for all real numbers We may rewrite this function as f(x) = cos –1 (sin x) = cos cos − −       1 π2 x = 2 x π − Thus f ′(x) = – 1
1
2451-2454
(i) cos –1 (sin x) (ii) 1 sin tan 1 cos x x −     +  (iii) 1 1 2 sin 1 4 x x + −     +  Solution (i) Let f (x) = cos –1 (sin x) Observe that this function is defined for all real numbers We may rewrite this function as f(x) = cos –1 (sin x) = cos cos − −       1 π2 x = 2 x π − Thus f ′(x) = – 1 (ii) Let f(x) = tan –1 sin 1 cos x x     + 
1
2452-2455
Observe that this function is defined for all real numbers We may rewrite this function as f(x) = cos –1 (sin x) = cos cos − −       1 π2 x = 2 x π − Thus f ′(x) = – 1 (ii) Let f(x) = tan –1 sin 1 cos x x     +  Observe that this function is defined for all real numbers, where cos x ≠ – 1; i
1
2453-2456
We may rewrite this function as f(x) = cos –1 (sin x) = cos cos − −       1 π2 x = 2 x π − Thus f ′(x) = – 1 (ii) Let f(x) = tan –1 sin 1 cos x x     +  Observe that this function is defined for all real numbers, where cos x ≠ – 1; i e
1
2454-2457
(ii) Let f(x) = tan –1 sin 1 cos x x     +  Observe that this function is defined for all real numbers, where cos x ≠ – 1; i e , at all odd multiplies of π
1
2455-2458
Observe that this function is defined for all real numbers, where cos x ≠ – 1; i e , at all odd multiplies of π We may rewrite this function as f(x) = 1 sin tan 1 cos x x −     +  = 1 2 2 sin 2cos 2 tan 2cos 2 x x x −                         Rationalised 2023-24 MATHEMATICS 142 = tan1 tan 2 2 x x −     =         Observe that we could cancel cos x2      in both numerator and denominator as it is not equal to zero
1
2456-2459
e , at all odd multiplies of π We may rewrite this function as f(x) = 1 sin tan 1 cos x x −     +  = 1 2 2 sin 2cos 2 tan 2cos 2 x x x −                         Rationalised 2023-24 MATHEMATICS 142 = tan1 tan 2 2 x x −     =         Observe that we could cancel cos x2      in both numerator and denominator as it is not equal to zero Thus f ′(x) = 1
1
2457-2460
, at all odd multiplies of π We may rewrite this function as f(x) = 1 sin tan 1 cos x x −     +  = 1 2 2 sin 2cos 2 tan 2cos 2 x x x −                         Rationalised 2023-24 MATHEMATICS 142 = tan1 tan 2 2 x x −     =         Observe that we could cancel cos x2      in both numerator and denominator as it is not equal to zero Thus f ′(x) = 1 2 (iii) Let f(x) = sin–1 1 12 4 x x +     + 
1
2458-2461
We may rewrite this function as f(x) = 1 sin tan 1 cos x x −     +  = 1 2 2 sin 2cos 2 tan 2cos 2 x x x −                         Rationalised 2023-24 MATHEMATICS 142 = tan1 tan 2 2 x x −     =         Observe that we could cancel cos x2      in both numerator and denominator as it is not equal to zero Thus f ′(x) = 1 2 (iii) Let f(x) = sin–1 1 12 4 x x +     +  To find the domain of this function we need to find all x such that 21 1 1 1 4 x x + − ≤ ≤ +
1
2459-2462
Thus f ′(x) = 1 2 (iii) Let f(x) = sin–1 1 12 4 x x +     +  To find the domain of this function we need to find all x such that 21 1 1 1 4 x x + − ≤ ≤ + Since the quantity in the middle is always positive, we need to find all x such that 1 2 1 1 4 x x + ≤ + , i
1
2460-2463
2 (iii) Let f(x) = sin–1 1 12 4 x x +     +  To find the domain of this function we need to find all x such that 21 1 1 1 4 x x + − ≤ ≤ + Since the quantity in the middle is always positive, we need to find all x such that 1 2 1 1 4 x x + ≤ + , i e
1
2461-2464
To find the domain of this function we need to find all x such that 21 1 1 1 4 x x + − ≤ ≤ + Since the quantity in the middle is always positive, we need to find all x such that 1 2 1 1 4 x x + ≤ + , i e , all x such that 2x + 1 ≤ 1 + 4x
1
2462-2465
Since the quantity in the middle is always positive, we need to find all x such that 1 2 1 1 4 x x + ≤ + , i e , all x such that 2x + 1 ≤ 1 + 4x We may rewrite this as 2 ≤ 1 2x + 2x which is true for all x
1
2463-2466
e , all x such that 2x + 1 ≤ 1 + 4x We may rewrite this as 2 ≤ 1 2x + 2x which is true for all x Hence the function is defined at every real number
1
2464-2467
, all x such that 2x + 1 ≤ 1 + 4x We may rewrite this as 2 ≤ 1 2x + 2x which is true for all x Hence the function is defined at every real number By putting 2x = tan θ, this function may be rewritten as f(x) = 1 1 2 sin 1 4 x x + −     +  = sin− ⋅ + ( )       1 2 2 2 1 2 x x = 1 2tan2 sin 1 tan − θ     + θ   = sin –1 [sin 2θ] = 2θ = 2 tan – 1 (2x) Thus f ′(x) = ( ) 2 1 2 (2 ) 1 2 x x dxd ⋅ ⋅ + = 2 (2 )log2 1 4 x x ⋅ + = 1 2 log2 1 4 x x + + Rationalised 2023-24 CONTINUITY AND DIFFERENTIABILITY 143 Example 41 Find f ′(x) if f(x) = (sin x)sin x for all 0 < x < π
1
2465-2468
We may rewrite this as 2 ≤ 1 2x + 2x which is true for all x Hence the function is defined at every real number By putting 2x = tan θ, this function may be rewritten as f(x) = 1 1 2 sin 1 4 x x + −     +  = sin− ⋅ + ( )       1 2 2 2 1 2 x x = 1 2tan2 sin 1 tan − θ     + θ   = sin –1 [sin 2θ] = 2θ = 2 tan – 1 (2x) Thus f ′(x) = ( ) 2 1 2 (2 ) 1 2 x x dxd ⋅ ⋅ + = 2 (2 )log2 1 4 x x ⋅ + = 1 2 log2 1 4 x x + + Rationalised 2023-24 CONTINUITY AND DIFFERENTIABILITY 143 Example 41 Find f ′(x) if f(x) = (sin x)sin x for all 0 < x < π Solution The function y = (sin x)sin x is defined for all positive real numbers
1
2466-2469
Hence the function is defined at every real number By putting 2x = tan θ, this function may be rewritten as f(x) = 1 1 2 sin 1 4 x x + −     +  = sin− ⋅ + ( )       1 2 2 2 1 2 x x = 1 2tan2 sin 1 tan − θ     + θ   = sin –1 [sin 2θ] = 2θ = 2 tan – 1 (2x) Thus f ′(x) = ( ) 2 1 2 (2 ) 1 2 x x dxd ⋅ ⋅ + = 2 (2 )log2 1 4 x x ⋅ + = 1 2 log2 1 4 x x + + Rationalised 2023-24 CONTINUITY AND DIFFERENTIABILITY 143 Example 41 Find f ′(x) if f(x) = (sin x)sin x for all 0 < x < π Solution The function y = (sin x)sin x is defined for all positive real numbers Taking logarithms, we have log y = log (sin x)sin x = sin x log (sin x) Then 1 dy y dx = d dx (sin x log (sin x)) = cos x log (sin x) + sin x
1
2467-2470
By putting 2x = tan θ, this function may be rewritten as f(x) = 1 1 2 sin 1 4 x x + −     +  = sin− ⋅ + ( )       1 2 2 2 1 2 x x = 1 2tan2 sin 1 tan − θ     + θ   = sin –1 [sin 2θ] = 2θ = 2 tan – 1 (2x) Thus f ′(x) = ( ) 2 1 2 (2 ) 1 2 x x dxd ⋅ ⋅ + = 2 (2 )log2 1 4 x x ⋅ + = 1 2 log2 1 4 x x + + Rationalised 2023-24 CONTINUITY AND DIFFERENTIABILITY 143 Example 41 Find f ′(x) if f(x) = (sin x)sin x for all 0 < x < π Solution The function y = (sin x)sin x is defined for all positive real numbers Taking logarithms, we have log y = log (sin x)sin x = sin x log (sin x) Then 1 dy y dx = d dx (sin x log (sin x)) = cos x log (sin x) + sin x 1 (sin ) sin d x x dx ⋅ = cos x log (sin x) + cos x = (1 + log (sin x)) cos x Thus dy dx = y((1 + log (sin x)) cos x) = (1 + log (sin x)) ( sin x)sin x cos x Example 42 For a positive constant a find dy dx , where 1 1 , and a t t y a x t t +   = = +    Solution Observe that both y and x are defined for all real t ≠ 0
1
2468-2471
Solution The function y = (sin x)sin x is defined for all positive real numbers Taking logarithms, we have log y = log (sin x)sin x = sin x log (sin x) Then 1 dy y dx = d dx (sin x log (sin x)) = cos x log (sin x) + sin x 1 (sin ) sin d x x dx ⋅ = cos x log (sin x) + cos x = (1 + log (sin x)) cos x Thus dy dx = y((1 + log (sin x)) cos x) = (1 + log (sin x)) ( sin x)sin x cos x Example 42 For a positive constant a find dy dx , where 1 1 , and a t t y a x t t +   = = +    Solution Observe that both y and x are defined for all real t ≠ 0 Clearly dy dt = ( ) t t1 d a dt + = 1 1 log at t d t a dt t +  + ⋅     = 1 12 1 log at t a t +   −    Similarly dx dt = 1 1 1 a d a t t t dt t −     + ⋅ +        = 1 2 1 1 1 a a t t t −     + ⋅ −        dx dt ≠ 0 only if t ≠ ± 1
1
2469-2472
Taking logarithms, we have log y = log (sin x)sin x = sin x log (sin x) Then 1 dy y dx = d dx (sin x log (sin x)) = cos x log (sin x) + sin x 1 (sin ) sin d x x dx ⋅ = cos x log (sin x) + cos x = (1 + log (sin x)) cos x Thus dy dx = y((1 + log (sin x)) cos x) = (1 + log (sin x)) ( sin x)sin x cos x Example 42 For a positive constant a find dy dx , where 1 1 , and a t t y a x t t +   = = +    Solution Observe that both y and x are defined for all real t ≠ 0 Clearly dy dt = ( ) t t1 d a dt + = 1 1 log at t d t a dt t +  + ⋅     = 1 12 1 log at t a t +   −    Similarly dx dt = 1 1 1 a d a t t t dt t −     + ⋅ +        = 1 2 1 1 1 a a t t t −     + ⋅ −        dx dt ≠ 0 only if t ≠ ± 1 Thus for t ≠ ± 1, Rationalised 2023-24 MATHEMATICS 144 dy dy dt dx dx dt = = a t a a t t t t t a + − −   +  ⋅ −   1 2 1 2 1 1 1 1 1 log = 1 1 log 1 t t a a a a t t + −  +    Example 43 Differentiate sin2 x w
1
2470-2473
1 (sin ) sin d x x dx ⋅ = cos x log (sin x) + cos x = (1 + log (sin x)) cos x Thus dy dx = y((1 + log (sin x)) cos x) = (1 + log (sin x)) ( sin x)sin x cos x Example 42 For a positive constant a find dy dx , where 1 1 , and a t t y a x t t +   = = +    Solution Observe that both y and x are defined for all real t ≠ 0 Clearly dy dt = ( ) t t1 d a dt + = 1 1 log at t d t a dt t +  + ⋅     = 1 12 1 log at t a t +   −    Similarly dx dt = 1 1 1 a d a t t t dt t −     + ⋅ +        = 1 2 1 1 1 a a t t t −     + ⋅ −        dx dt ≠ 0 only if t ≠ ± 1 Thus for t ≠ ± 1, Rationalised 2023-24 MATHEMATICS 144 dy dy dt dx dx dt = = a t a a t t t t t a + − −   +  ⋅ −   1 2 1 2 1 1 1 1 1 log = 1 1 log 1 t t a a a a t t + −  +    Example 43 Differentiate sin2 x w r
1
2471-2474
Clearly dy dt = ( ) t t1 d a dt + = 1 1 log at t d t a dt t +  + ⋅     = 1 12 1 log at t a t +   −    Similarly dx dt = 1 1 1 a d a t t t dt t −     + ⋅ +        = 1 2 1 1 1 a a t t t −     + ⋅ −        dx dt ≠ 0 only if t ≠ ± 1 Thus for t ≠ ± 1, Rationalised 2023-24 MATHEMATICS 144 dy dy dt dx dx dt = = a t a a t t t t t a + − −   +  ⋅ −   1 2 1 2 1 1 1 1 1 log = 1 1 log 1 t t a a a a t t + −  +    Example 43 Differentiate sin2 x w r t
1
2472-2475
Thus for t ≠ ± 1, Rationalised 2023-24 MATHEMATICS 144 dy dy dt dx dx dt = = a t a a t t t t t a + − −   +  ⋅ −   1 2 1 2 1 1 1 1 1 log = 1 1 log 1 t t a a a a t t + −  +    Example 43 Differentiate sin2 x w r t e cos x
1
2473-2476
r t e cos x Solution Let u (x) = sin2 x and v (x) = e cos x
1
2474-2477
t e cos x Solution Let u (x) = sin2 x and v (x) = e cos x We want to find / / du du dx dv =dv dx
1
2475-2478
e cos x Solution Let u (x) = sin2 x and v (x) = e cos x We want to find / / du du dx dv =dv dx Clearly du dx = 2 sin x cos x and dv dx = e cos x (– sin x) = – (sin x) e cos x Thus du dv = cos cos 2sin cos 2cos sin x x x x x x e = −e − Miscellaneous Exercise on Chapter 5 Differentiate w
1
2476-2479
Solution Let u (x) = sin2 x and v (x) = e cos x We want to find / / du du dx dv =dv dx Clearly du dx = 2 sin x cos x and dv dx = e cos x (– sin x) = – (sin x) e cos x Thus du dv = cos cos 2sin cos 2cos sin x x x x x x e = −e − Miscellaneous Exercise on Chapter 5 Differentiate w r
1
2477-2480
We want to find / / du du dx dv =dv dx Clearly du dx = 2 sin x cos x and dv dx = e cos x (– sin x) = – (sin x) e cos x Thus du dv = cos cos 2sin cos 2cos sin x x x x x x e = −e − Miscellaneous Exercise on Chapter 5 Differentiate w r t
1
2478-2481
Clearly du dx = 2 sin x cos x and dv dx = e cos x (– sin x) = – (sin x) e cos x Thus du dv = cos cos 2sin cos 2cos sin x x x x x x e = −e − Miscellaneous Exercise on Chapter 5 Differentiate w r t x the function in Exercises 1 to 11
1
2479-2482
r t x the function in Exercises 1 to 11 1
1
2480-2483
t x the function in Exercises 1 to 11 1 (3x2 – 9x + 5)9 2
1
2481-2484
x the function in Exercises 1 to 11 1 (3x2 – 9x + 5)9 2 sin3 x + cos6 x 3
1
2482-2485
1 (3x2 – 9x + 5)9 2 sin3 x + cos6 x 3 (5x)3 cos 2x 4
1
2483-2486
(3x2 – 9x + 5)9 2 sin3 x + cos6 x 3 (5x)3 cos 2x 4 sin–1(x x ), 0 ≤ x ≤ 1 5
1
2484-2487
sin3 x + cos6 x 3 (5x)3 cos 2x 4 sin–1(x x ), 0 ≤ x ≤ 1 5 cos1 2 2 7 x x − + , – 2 < x < 2 6
1
2485-2488
(5x)3 cos 2x 4 sin–1(x x ), 0 ≤ x ≤ 1 5 cos1 2 2 7 x x − + , – 2 < x < 2 6 1 1 sin 1 sin cot 1 sin 1 sin x x x x −   + + −   + − −   , 0 < x < 2 π 7
1
2486-2489
sin–1(x x ), 0 ≤ x ≤ 1 5 cos1 2 2 7 x x − + , – 2 < x < 2 6 1 1 sin 1 sin cot 1 sin 1 sin x x x x −   + + −   + − −   , 0 < x < 2 π 7 (log x)log x, x > 1 8
1
2487-2490
cos1 2 2 7 x x − + , – 2 < x < 2 6 1 1 sin 1 sin cot 1 sin 1 sin x x x x −   + + −   + − −   , 0 < x < 2 π 7 (log x)log x, x > 1 8 cos (a cos x + b sin x), for some constant a and b
1
2488-2491
1 1 sin 1 sin cot 1 sin 1 sin x x x x −   + + −   + − −   , 0 < x < 2 π 7 (log x)log x, x > 1 8 cos (a cos x + b sin x), for some constant a and b 9
1
2489-2492
(log x)log x, x > 1 8 cos (a cos x + b sin x), for some constant a and b 9 (sin x – cos x) (sin x – cos x), 3 4 4 x π π < < 10
1
2490-2493
cos (a cos x + b sin x), for some constant a and b 9 (sin x – cos x) (sin x – cos x), 3 4 4 x π π < < 10 xx + xa + ax + aa, for some fixed a > 0 and x > 0 Rationalised 2023-24 CONTINUITY AND DIFFERENTIABILITY 145 11
1
2491-2494
9 (sin x – cos x) (sin x – cos x), 3 4 4 x π π < < 10 xx + xa + ax + aa, for some fixed a > 0 and x > 0 Rationalised 2023-24 CONTINUITY AND DIFFERENTIABILITY 145 11 ( ) 2 2 3 3 x xx − +x − , for x > 3 12
1
2492-2495
(sin x – cos x) (sin x – cos x), 3 4 4 x π π < < 10 xx + xa + ax + aa, for some fixed a > 0 and x > 0 Rationalised 2023-24 CONTINUITY AND DIFFERENTIABILITY 145 11 ( ) 2 2 3 3 x xx − +x − , for x > 3 12 Find dy dx , if y = 12 (1 – cos t), x = 10 (t – sin t), 2 2 t π π − < < 13
1
2493-2496
xx + xa + ax + aa, for some fixed a > 0 and x > 0 Rationalised 2023-24 CONTINUITY AND DIFFERENTIABILITY 145 11 ( ) 2 2 3 3 x xx − +x − , for x > 3 12 Find dy dx , if y = 12 (1 – cos t), x = 10 (t – sin t), 2 2 t π π − < < 13 Find dy dx , if y = sin–1 x + sin–1 2 1 −x , 0 < x < 1 14
1
2494-2497
( ) 2 2 3 3 x xx − +x − , for x > 3 12 Find dy dx , if y = 12 (1 – cos t), x = 10 (t – sin t), 2 2 t π π − < < 13 Find dy dx , if y = sin–1 x + sin–1 2 1 −x , 0 < x < 1 14 If 1 1 0 x y y x + + + = , for , – 1 < x < 1, prove that ( )2 1 1 dy dx x = − + 15
1
2495-2498
Find dy dx , if y = 12 (1 – cos t), x = 10 (t – sin t), 2 2 t π π − < < 13 Find dy dx , if y = sin–1 x + sin–1 2 1 −x , 0 < x < 1 14 If 1 1 0 x y y x + + + = , for , – 1 < x < 1, prove that ( )2 1 1 dy dx x = − + 15 If (x – a)2 + (y – b)2 = c2, for some c > 0, prove that 3 2 2 2 2 1 dy dx d y dx     +        is a constant independent of a and b
1
2496-2499
Find dy dx , if y = sin–1 x + sin–1 2 1 −x , 0 < x < 1 14 If 1 1 0 x y y x + + + = , for , – 1 < x < 1, prove that ( )2 1 1 dy dx x = − + 15 If (x – a)2 + (y – b)2 = c2, for some c > 0, prove that 3 2 2 2 2 1 dy dx d y dx     +        is a constant independent of a and b 16
1
2497-2500
If 1 1 0 x y y x + + + = , for , – 1 < x < 1, prove that ( )2 1 1 dy dx x = − + 15 If (x – a)2 + (y – b)2 = c2, for some c > 0, prove that 3 2 2 2 2 1 dy dx d y dx     +        is a constant independent of a and b 16 If cos y = x cos (a + y), with cos a ≠ ± 1, prove that cos (2 ) sin dy a y dx +a =
1
2498-2501
If (x – a)2 + (y – b)2 = c2, for some c > 0, prove that 3 2 2 2 2 1 dy dx d y dx     +        is a constant independent of a and b 16 If cos y = x cos (a + y), with cos a ≠ ± 1, prove that cos (2 ) sin dy a y dx +a = 17
1
2499-2502
16 If cos y = x cos (a + y), with cos a ≠ ± 1, prove that cos (2 ) sin dy a y dx +a = 17 If x = a (cos t + t sin t) and y = a (sin t – t cos t), find 2 2 d y dx
1
2500-2503
If cos y = x cos (a + y), with cos a ≠ ± 1, prove that cos (2 ) sin dy a y dx +a = 17 If x = a (cos t + t sin t) and y = a (sin t – t cos t), find 2 2 d y dx 18
1
2501-2504
17 If x = a (cos t + t sin t) and y = a (sin t – t cos t), find 2 2 d y dx 18 If f(x) = | x |3, show that f ″(x) exists for all real x and find it
1
2502-2505
If x = a (cos t + t sin t) and y = a (sin t – t cos t), find 2 2 d y dx 18 If f(x) = | x |3, show that f ″(x) exists for all real x and find it 19
1
2503-2506
18 If f(x) = | x |3, show that f ″(x) exists for all real x and find it 19 Using the fact that sin (A + B) = sin A cos B + cos A sin B and the differentiation, obtain the sum formula for cosines
1
2504-2507
If f(x) = | x |3, show that f ″(x) exists for all real x and find it 19 Using the fact that sin (A + B) = sin A cos B + cos A sin B and the differentiation, obtain the sum formula for cosines 20
1
2505-2508
19 Using the fact that sin (A + B) = sin A cos B + cos A sin B and the differentiation, obtain the sum formula for cosines 20 Does there exist a function which is continuous everywhere but not differentiable at exactly two points
1
2506-2509
Using the fact that sin (A + B) = sin A cos B + cos A sin B and the differentiation, obtain the sum formula for cosines 20 Does there exist a function which is continuous everywhere but not differentiable at exactly two points Justify your answer
1
2507-2510
20 Does there exist a function which is continuous everywhere but not differentiable at exactly two points Justify your answer 21
1
2508-2511
Does there exist a function which is continuous everywhere but not differentiable at exactly two points Justify your answer 21 If ( ) ( ) ( ) f x g x h x y l m n a b c = , prove that ( ) ( ) ( ) f x g x h x dy l m n dx a b c ′ ′ ′ = 22
1
2509-2512
Justify your answer 21 If ( ) ( ) ( ) f x g x h x y l m n a b c = , prove that ( ) ( ) ( ) f x g x h x dy l m n dx a b c ′ ′ ′ = 22 If y = acos1 x e − , – 1 ≤ x ≤ 1, show that ( ) 2 2 2 2 1 0 d y dy x x a y dx dx − − − =
1
2510-2513
21 If ( ) ( ) ( ) f x g x h x y l m n a b c = , prove that ( ) ( ) ( ) f x g x h x dy l m n dx a b c ′ ′ ′ = 22 If y = acos1 x e − , – 1 ≤ x ≤ 1, show that ( ) 2 2 2 2 1 0 d y dy x x a y dx dx − − − = Rationalised 2023-24 MATHEMATICS 146 Summary ® A real valued function is continuous at a point in its domain if the limit of the function at that point equals the value of the function at that point
1
2511-2514
If ( ) ( ) ( ) f x g x h x y l m n a b c = , prove that ( ) ( ) ( ) f x g x h x dy l m n dx a b c ′ ′ ′ = 22 If y = acos1 x e − , – 1 ≤ x ≤ 1, show that ( ) 2 2 2 2 1 0 d y dy x x a y dx dx − − − = Rationalised 2023-24 MATHEMATICS 146 Summary ® A real valued function is continuous at a point in its domain if the limit of the function at that point equals the value of the function at that point A function is continuous if it is continuous on the whole of its domain
1
2512-2515
If y = acos1 x e − , – 1 ≤ x ≤ 1, show that ( ) 2 2 2 2 1 0 d y dy x x a y dx dx − − − = Rationalised 2023-24 MATHEMATICS 146 Summary ® A real valued function is continuous at a point in its domain if the limit of the function at that point equals the value of the function at that point A function is continuous if it is continuous on the whole of its domain ® Sum, difference, product and quotient of continuous functions are continuous
1
2513-2516
Rationalised 2023-24 MATHEMATICS 146 Summary ® A real valued function is continuous at a point in its domain if the limit of the function at that point equals the value of the function at that point A function is continuous if it is continuous on the whole of its domain ® Sum, difference, product and quotient of continuous functions are continuous i
1
2514-2517
A function is continuous if it is continuous on the whole of its domain ® Sum, difference, product and quotient of continuous functions are continuous i e
1
2515-2518
® Sum, difference, product and quotient of continuous functions are continuous i e , if f and g are continuous functions, then (f ± g) (x) = f (x) ± g(x) is continuous
1
2516-2519
i e , if f and g are continuous functions, then (f ± g) (x) = f (x) ± g(x) is continuous (f
1
2517-2520
e , if f and g are continuous functions, then (f ± g) (x) = f (x) ± g(x) is continuous (f g) (x) = f (x)