Maximum value of the function f(x) = x8 + 2x on th

Subject

Mathematics

Class

JEE Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

61.

Let y = 3x - 13x + 1sinx + loge1 + x, x > - 1. Then, at x = 0, dydx equals

  • 1

  • 0

  • - 1

  • - 2


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62.

Maximum value of the function f(x) = x8 + 2x on the interval [1, 6] is

  • 1

  • 98

  • 1312

  • 178


D.

178

fx = x8 +2x

 f'(x)= 18 - 2x2 = x2 - 168x2

For maximum or minimum f' (x)must be vanish.

          f'(x) = 0 x2 - 168x2 = 0             x = 4, - 4 x  1, 6 x  - 4

Also, in [1, 4], f'(x) < 0  f(x) is decreasing.

In [4, 6], f'(x) > 0 ⇒ f(x) is increasing.

f1 = 18 + 21 = 178

f8 = 68 + 26 = 34 + 13 = 1312

Hence, maximum value of f (x) in [1, 6] is 178


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63.

For  - π2 < x < 3π2, the avlue of ddxtan-1cosx1 + sinx is equal to

  • 12

  • 12

  • 1

  • sinx1 + sinx2


64.

If f is a real-valued differentiable function such that f(x)f' (x) < 0 for all real x, then

  • f(x) must be an increasing function

  • f(x) must be a decreasing function

  • f(x) must be an increasing function

  • f(x) must be a decreasing function


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65.

Rolle's theorem is applicable in the interval [- 2, 2] for the function

  • f(x) = x3

  • f(x) = 4x4

  • f(x) = 2x3 + 3

  • f(x) = πx


66.

The solution of 25d2ydx2 - 10dydx + y = 0, y(0) = 1, y(1) = 2e15 is

  • y = e5x + e- 5x

  • y = 1 + xe5x

  • y = 1 + xex5

  • y = 1 + xe- x5


67.

The system of linear equations λx + y + z = 3,  x - y - 2z = 6, - x + y + z = µ has

  • infinite number of solutions for λ -1 and all µ

  • infinite number of solutions for λ = - 1 and μ = 3

  • no solution for λ  - 1

  • unique solution for λ = - 1 and μ = 3


68.

If f(x) and g(x) are twice differentiable functions on (0, 3) satisfying f"(x) = g''(c), f'(1) = 4g'(D) = 6, f(2) = 3, g(2) = 9, then f(1) - g(1) is

  • 4

  • - 4

  • 0

  • - 2


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69.

Two coins are available, one fair and the other two headed. Choose a coin and toss it once; assume that the unbiased coin is chosen with probability 34. Given that the outcome is head, 4 the probability that the two headed coin was chosen, is

  • 35

  • 25

  • 15

  • 27


70.

The general solution of the differential equation

dydx = x +y +12x +2y +1 is

  • loge3x + 3y + 2 + 3x + 6y = C

  • loge3x + 3y + 2 - 3x + 6y = C

  • loge3x + 3y + 2 - 3x - 6y = C

  • loge3x + 3y + 2 + 3x - 6y = C


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