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MHT CET2019Morning ShiftMathematicsApplication of DerivativesActual

The edge of a cube is decreasing at the rate of 0.04 cm/sec. If the edge of the cube is 10 cms, then rate of decrease of surface area of the cube is …

Options

  1. A4.8 c m 2 s e c
  2. B4.08 c m 2 s e c
  3. C48 c m 2 s e c
  4. D4.008 c m 2 s e c

Correct answer

A. 4.8 c m 2 s e c

Step-by-step solution

Let edge of a cube be x cm, then surface area of the cube, A = 6 x 2 It is given that, d x d t = - 0.04 cm/sec Now, d A d t = 12 x d x d t = 12 x - 0.04 = - 0.48 x when, x = 10 , then d A d t = 0.48 × 10 = - 4.8 c m 2 s e c

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