Question

A square has a side length that is decreasing at a rate of 8 cm per second. What is the rate of change of the area of the square when the side length is 7 cm

Answer 1

Answer:

112cm²/sec

Step-by-step explanation:

Area of a square is expressed as A = L² where L is the length of one side of the square.

The rate of change of area will be expressed  using chain rule as;

dA/dt = dA/dL * dL/dt where;

dL/dt is the rate at which the side length of the square is decreasing.

Given L = 7cm, dL/dt = 8cm/sec and dA/dL = 2L

dA/dL = 2(7)

dA/dL = 14cm

Substituting the given value into the chain rule expression above to get the rate of change of the area of the square, we will have;

dA/dt = dA/dL * dL/dt

dA/dt = 14cm * 8cm/sec

dA/dt = 112cm²/sec

Hence, the rate of change of the area of the square when the side length is 7 cm is 112cm²/sec