Question

A rectangle has length (x + 5)cm and width (x –2)cm. Its area is 60 cm 2

Answer 1

Area = length x width

60 = (x+5) (x-2)

60 = x^2 + 3x -10

Subtract 60 from both sides:

x^2 +3x -70 = 0

Solve for x by finding 2 numbers when added together = 3 and when multiplied by each other = -70

x = -10 and 7

Since the sides have to be a positive number we need to use 7

The length = x+5 = 7+5 = 12 cm

The width = x-2 = 7-2 = 5 cm