Application of DerivativeHard
Question
The surface area of a cube is increasing at the rate of 2 cm2/sec. When its edge is 90 cm, the volume is increasing at the rate of-
Options
A.1620 cm3/sec
B.810 cm3/sec
C.405 cm3/sec
D.45 cm3/sec
Solution
A = 6x2 x = edge of cube
= 2 = 12 × x × 
2 = 12 × 90 ×
= 3x2 × = 3 × 90 × 90 × 
= 45 cm3/sec
= 2 = 12 × x × 2 = 12 × 90 ×
= 3x2 × = 3 × 90 × 90 × = 45 cm3/secCreate a free account to view solution
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