Question

The volume of a cube is increasing at a rate of 9cm3 per second .How fast is the surface area increasing when the length of an edge is 10 cm.

Answer 1

Answer:

18/5

Step-by-step explanation:

d(V)/dt = 9

d(a³)/dt = 9

3a²(da/dt) = 9

a²(da/dt) = 3

When a= 10, da/dt = 3/100

Surface area :

d(6a²)/dt = 6 * 2a * (da/dt)

               = 12*(10)*(3/100) = 18/5