If y = x + 1 + x2n, then 

Subject

Mathematics

Class

JEE Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

11.

The domain of sin-1log3x3 is

  • [1, 9]

  • [- 1, 9]

  • [- 9, 1]

  • [- 9, - 1]


12.

The value of m for which the function f(x) = mx2, x  1  2x, x > 1, is differentiable at x = 1, is

  • 0

  • 1

  • 2

  • does not exist


13.

If y = (1 + x1/4)(1 + x1/2)(1 - x1/4), then dy/dx is equal to

  • 1

  • - 1

  • x

  • x


14.

If y = loglogx, then eydydx is equal to

  • 1xlogx

  • 1x

  • 1logx

  • ey


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15.

For the function f(x) = x2 - 6x + 8, 2  x  4, the value of x for which f'(x) vanishes, is

  • 9/4

  • 5/2

  • 3

  • 7/2


16.

The function f(x) = cot-1(x) + x, increases in the interval

  • 1, 

  • - 1, 

  • - , 

  • 0, 


17.

For all real values of x, increasing function is

  • x- 1

  • x2

  • x3

  • x4


18.

Maximum value of f(x) = sin(x) + cos(x) is

  • 1

  • 2

  • 12

  • 2


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19.

The greatest value of f(x) = (x + 1)1/3 - (x - 1)1/3 on [0, 1] is

  • 1

  • 2

  • 3

  • 1/3


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20.

If y = x + 1 + x2n, then 1 + x2d2ydx2 + xdydx is equal to

  • n2y

  • - n2y

  • - y

  • 2x2y


A.

n2y

Given, y = x + 1 + x2nOn differentiating w.r.t. x, we getdydx = nx + 1 + x2n - 1 . 1 + 1 . 2x21 + x2      = nx + 1 + x2n1 + x2 = ny1 + x2 1 + x2dydx = nyOn squarmg both sides, we get1 + x2dydx2 = n2y2Again, differentiating w.r.t. x, we get1 + x22dydxd2ydx2 + dydx22x = n2 . 2ydydx 1 + x2d2ydx2 + xdydx = n2y


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