If a circular plate is heated uniformly, its area expands 3c time

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 Multiple Choice QuestionsMultiple Choice Questions

541.

The slope of the normal to the curve y = x21x2 at (- 1, 0) is

  • 14

  • - 14

  • 4

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542.

The minimum value of sin(x) + cos(x) is

  • 2

  • - 2

  • 12

  • - 12


543.

The slope of the tangent to the curve y = 3x2 - 5x + 6 at (1, 4) is

  • - 2

  • 1

  • 0

  • - 1


544.

The chord joining the points (5, 5) and (11, 227) on the curve y = 3x2 - 11x - 15 is parallel to tangent at a point on the curve. Then, the abscissa of the point is

  • - 4

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  • - 8

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545.

The function f(x) = sin(x) - kx - c, where k and c are constants, decreases always when

  • k > 1

  • k  1

  • k < 1

  • k  1


546.

If y = mlog(x) + nx2 + x has its extreme values at x = 2 and x = 1, then 2m + 10n is equal to

  • - 1

  • - 4

  • - 2

  • - 3


547.

If s = 2t3 - 6t2 + at + 5 is the distance travelled by a particle at time t and if the velocity is - 3 when its acceleration is zero, then the value of a is

  • - 3

  • 3

  • 4

  • - 4


548.

Let f(x) = [3 sin2(10x + 11) - 7]2 for x  R. Then, the maximum value of the function f is

  • 9

  • 16

  • 49

  • 100


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549.

If a circular plate is heated uniformly, its area expands 3c times as fast as its radius, then the value of c when the radius is 6 units, is

  • 4π

  • 2π

  • 6π

  • 3π


A.

4π

Let area of the circular plate be A and its radius be r.

Then, A = πr2 On differentiating both sides w.r.t. t, we get     dAdt = 2πrdrdtBut dAdt = 3cdrdt 3cdrdt = 2πrdrdt     3c = 2πrOn putting r = 6, we get           c = 4π


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550.

The minimum valuje of 2x3 - 9x2 + 12x + 4 is

  • 4

  • 5

  • 6

  • 8


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