Question

The width of a rectangle is 3 units less than the length. The area of the rectangle is 18

units. What is the length, in units, of the rectangle?

Answer 1

First let the length be a variable (eg: x) so that we can form an expression and solve.

Let the length of the rectangle be x units.

Form an expression for the width of the rectangle using the information given.

Width = (x - 3) units

Area of rectangle = length x width

Using the formula, form an equation.

x(x - 3) = 18

Simplify and solve for x.

x² - 3x = 18

x² - 3x - 18 = 0

(x - 6)(x + 3) = 0

x - 6 = 0 or x + 3 = 0

x = 6 or x = - 3 (reject)

The length cannot have a negative value so reject - 3.

Hence, the length of the rectangle is 6 units.