The tangent to the curve xy = 25 at any point on it cuts the coor

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 Multiple Choice QuestionsMultiple Choice Questions

691.

If a ball is thrown vertically upwards and the height 's' reached in time 't' is given by s = 22t - 11t2, then the total distance travelled by the ball is

  • 44 units

  • 33 units

  • 11 units

  • 22 units


692.

The sum of two positive numbers is given. If the sum of their cubes is minimum, then

  • they are equal

  • one is twice the other

  • they are unequal

  • one is thrice the other


693.

The perimeter of a sectoris a constant. Ifits area is to be maximum, then the sectorial angle is

  • πc6

  • πc4

  • 4c

  • 2c


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694.

The tangent to the curve xy = 25 at any point on it cuts the coordinate axes at A and B, then the area of the OAB is

  • 50 sq units

  • 25 sq units

  • 75 sq units

  • 100 sq units


A.

50 sq units

Given, curve xy = 25     ...(i)

On differentiating Eq. (i), w.r.t. 'x', we get

           xdydx + y = 0              xdydx = - y                dydx = - yx dydxat x1, y1 = - y1x1The equation of tangent at the point (x1, y1) is given by          y -  y1 = dydxat x1, y1x - x1      y -  y1 = - y1x1x - x1 x1y - x1y1 = - xy1 + x1y1On dividing throughout by 2x1y1 , we getx2x1 + y2y1 = 1        ....ii

Since, (x1, y1) satisfy the curve xy = 25 x1y1 = 25         ...iii Requited area of OAB            = 12 × OA × OB            = 12 × 2x1 × 2y1           = 2 × x1y1           = 2x1 × 25x1        from Eq. (iii)           = 50 sq units.


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695.

The length of the subtangent, ordinate and the subnormal are in

  • AP

  • HP

  • GP

  • Arithmetico-geometric progression


696.

The maximum value of xe-x is

  • e

  • 1e

  • - e

  • 1e


697.

The maximum area of a rectangle that can be inscribed in a circle of radius 2 units is

  • 8π sq units

  • 4 sq units

  • 5 sq units

  • 8 sq units


698.

If the length of the subtangent at any point to the curve xyn = a is proportional to the abscissa, then n is

  • any non-zero real number

  • 2

  • - 2

  • 1


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699.

The function f(x) = x3 + 3x decreases in the interval

  • (- 3, 3)

  • - , 3

  • 3, 

  • (- 9, 9)


700.

The tangent to the curve y = x3 + 1 at (1, 2) makes an angle θ with y-axis, then the value of tanθ is

  • - 13

  • 3

  • - 3

  • 13


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