Question 505410
The area of a rectangle is 72 square inches.
L * W = 72 sq/in
:
 If the length is 40 inches greater than four times the width,
L = 4W+40
:
In the 1st equation, replace L with (4W+40)
(4W+40) * W = 72
4W^2 + 40W = 72
Simplify, divide by 4
W^2 + 10W = 18
A quadratic equation
W^2 + 10W - 18 = 0
Won't factor, have to solve it with the quadratic formula
a=1; b=10; c= -18
The positive solution = 1.55743852" is the width of the rectangle
then
4(1.55743852) + 40 = 46.22975408" is the length
:
Confirm this by finding the area using these two dimensions