Question

Each side of a square is increasing at a rate of 5 cm/s. At what rate is the area of the square increasing when the area of the square is 49 cm2

Answer 1

70cm/s

Explanation:

Area of a square with side of length L is expressed as A = L². The rate at which the area is increasing will be expressed as dA/dt.

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

dL/dt is the rate at which each side of the square is increasing.

Since dA/dL = 2L, dA/dt = 2L dL/dt

Given dL/dt = 5cm/s and the Area of the square = 49 cm²

49 = L²

L = √49

L = 7cm

dA/dt = 2(7) * 5

dA/dt = 14*5

dA/dt = 70cm/s

The rate at which the area of the square is increasing is 70cm/s