Find the length of the rectangle

Question

A rectangle is drawn so that the width is 4 feet shorter than the length. The area of the rectangle is 21 square feet. Find the length of the rectangle.

Answer 1

Hi Silvana,

 

Let length = L

     width = L - 4   (4 feet shorter

 

Area = lenth * width

 

21 = L * (L-4)

 

21 = L² - 4L

 

0 = L² - 4L - 21

 

0 = (L -7)(L+3)

 

solve for the positive value of L since lenght will be positive

 

0 = L - 7

 

L = 7         (lenght = 7

 

width = 7 -4

         = 3

 

Hope this helps