If f(x) = x3 - 3x + 2,   

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 Multiple Choice QuestionsMultiple Choice Questions

661.

Let f be any continuously differentiable function on [a, b] and twice differentiable on (a, b) such that f(a) = f"(a) = 0 and f(b) = 0. Then,

  • f''(a) = 0

  • f'(x) = 0 for some x  a, b

  • f''(x)  0 for some x  a, b

  • f'''x = 0 for some x  a, b


662.

Let f : R  R  be such that f(2x - 1) = f(x) for all x  R. If f is continuous at x = 1 and f(1) = 1, then

  • f(2) = 1

  • f(2) = 2

  • f is continuous only at x = 1

  • f is continuous at all points


663.

Let f(x) be a differentiable function in [2, 7]. If f(2) = 3 and f'(x)  5 for all x in (2, 7), then the maximum possible value of f(x) at x = 7 is

  • 7

  • 15

  • 28

  • 14


664.

The function f(x) = tanπx - π22 + x2, where x denotes the greatest integer  x, is

  • continuous for all values of x

  • discontinuous at x = π2

  • not differentiable for some values of x

  • discontinuous at x = - 2


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665.

The function f (x) = f(x) = asinx + bex is differentiable at x = 0 when

  • 3a + b = 0

  • 3a - b = 0

  • a + b = 0

  • a - b = 0


666.

Let R be the set of all real numbers and f : [- 1, 1]  R be defined by

f(x) = xsin1x,     x  00,                 x = 0 Then,

  • f satisfies tile conditions of Rolle's theorem on [-1, 1]

  • f satisfies the conditions of Lagrange's mean value theorem on [-1, 1]

  • f satisfies the conditions of Rolle's theorem on [0, 1]

  • f satisfies the conditions of Lagrange's mean value theorem on [0, 1]


667.

Suppose that f(x) is a differentiable function such that f'(x) is continuous, f'(0) = 1 and f''(0) does not exist. Let g(x) = xf'(x), Then,

  • g'(0) does not exist

  • g'(0) = 0

  • g'(0) = 1

  • g'(0) = 2


668.

Applying Lagrange's Mean Value Theorem for a suitable function f(x) in [0, h], we have f(h) = f(0) + hf'(θh), 0 < θ < 1. Then, for f(x) = cos(x), the value of limh0+θ is

  • 1

  • 0

  • 1/2

  • 1/3


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669.

Let f(x) = 0x1 - tdt,    x > 0x - 12,         x  1. Then

  • f(x) is continuous at x = 1

  • f(x) is not continuous at x = 1

  • f(x) is differentiable at x = 1

  • f(x) is not differentiable at x = 1


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670.

If f(x) = x3 - 3x + 2,                      x < 2,x3 - 6x2 + 9x + 2,           x  2

then

  • limx2f(x) does not exist

  • f is not continuous at x = 2

  • f is continuous but not differentiable at x = 2

  • f is continuous and differentiable at x = 2


C.

f is continuous but not differentiable at x = 2

Given,x3 - 3x + 2,                      x < 2,x3 - 6x2 + 9x + 2,           x  2LHL = f2 - 0 = limh0f2 - 03 - 32 - h + 2                          = 23 - 6 + 2                          = 8 - 6 + 2                          = 4

RHL = f(2 + 0) = limh02 + h3 - 62 + h2 + 92 + h + 2                          = 23 - 622 + 92 + 2                          = 8 - 24 + 18 + 2                          = 4              LHL = RHL limx2f(x) exist

and f(2) = (2)3 - 6(2)2 + 9(2) + 2

             = 8 - 24 + 18 + 2

             = 4

 LHL = RHL = f(2)

So, f(x) is continuous at x = 2

Now, f'(x) = 3x2 - 3,                 x < 23x2 - 12x + 9,     x  2   Lf'(2) = 322 - 3                = 12 - 3 = 9and Rf'(2) = 322 - 122 + 9                = 12 - 24 + 9 = - 3   Lf'(2)  Rf'(2)

Thus, f(x) is not differentiable at x = 2

Hence, f is continuous but not differentiable at x = 2.


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