how to do this

Question

The length of a rectangle is 2

centimeters less than its width. What are the dimensions of the rectangle if its area is 80

square centimeters?

Answer 1

Hi Miriam, let l represent the length and w the width. Area is given by l * w. Here l = w - 2.

 

Equation to solve:

 

l * w = 80

 

Substitute for l:

 

(w - 2) * w = 80

 

w² - 2w = 80

 

Rewrite:

 

w² -2w - 80 = 0

 

Factor:

 

(w - 10) * (w + 8) = 0

 

Apply the zero product rule:

 

w - 10 = 0

 

w = 10

 

w + 8 = 0

 

w = -8, we can discard this result since the width cannot be negative.

 

Answer:

 

Width is 10 centimeters.

 

Length is 10 - 2, or 8 centimeters.

 

Check:

 

Area = l * w

 

80 = 8 * 10

 

80 = 80

 

Values check.

 

Questions?