The values of a and b for which the function y = aloge(x ) + bx2

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 Multiple Choice QuestionsMultiple Choice Questions

621.

The function y = 2x - x2

  • increases in (0, 1) but decreases in (1, 2)

  • decreases in (0, 2)

  • increases m (1, 2) but decreases in (0, 1)

  • increases in (0, 2)


622.

The interval in which the function y = x - 2sinx0  x  2π increases throughout is

  • 5π3, 2π

  • 0, π3

  • π3, 5π3

  • 0, π4


623.

The points of the curve y = x3 + x - 2 at which its tangent are parallel to the straight line y = 4x - 1 are

  • (2, 7), (- 2, - 11)

  • (0, 2), (21/3, 21/3)

  • (- 21/3, - 21/3), (0, - 4)

  • (1, 0), (- 1, - 4)


624.

The equation of the normal to the curve y = - x + 2 at the point of its intersection with the bisector of the first quadrant is

  • 4x - y + 16 = 0

  • 4x - y = 16

  • 2x - y - 1 = 0

  • 2x - y + 1 = 0


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625.

The angle at which the curve y = x2 and the curve x = 53cost, y = 54sint intersect is

  • tan-1241

  • tan-1412

  • - tan-1241

  • 2tan-1412


626.

The maximum value of the function y = 2tanx - tan2x over 0, π2 is

  • 1

  • 3

  • 2


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627.

The values of a and b for which the function y = aloge(x ) + bx2 + x, has extremum at the points x1 = 1 and x2 = 2 are

  • a = 23, b = - 16

  • a = - 23, b = - 16

  • a = - 23, b = 16

  • a = - 13, b = - 16


B.

a = - 23, b = - 16

iven, y = alogex + bx2 + x    ...i dydx = a × 1x + 2bx + 1     ...iiAt the point of maxima, dydx = 0 ax + 2bx + 1 = 0               ...(iii)According to question for x = 1 and x = 2 satisfy Eq. (iii)    a + 2b + 1 = 0              ...(iv)And a2 + 4b + 1 = 0              ...(v)By solving Eqs, (iv) and (v)a = - 23, b = - 16


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628.

The value of maxima of 1xx is

  • 1ee

  • ee

  • e

  • e1/e


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629.

A point particle moves along a straight line such that x = t, where t is time. Then, ratio of acceleration to cube of the velocity is

  • - 1

  • - 0.5

  • - 3

  • - 2


630.

The tangents to curve y = x3 - 2x2 + x - 2 which are parallel to straight line y = x, are

  • x + y = 2 and x - y = 8627

  • x - y = 2 and x - y = 8627

  • x - y = 2 and x + y = 8627

  • x + y = 2 and x + y = 8627


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