Question

A rectangle has a length that is 9 feet less than four times its width. Its area is 90 square feet

Answer 1

The length of rectangle is
`15\ ft`

The width of rectangle is
`6\ ft`

Explanation:

Let

x-----> the length of rectangle

y----> the width of rectangle

we know that

The area of rectangle is equal to

`A=xy`

`A=90\ ft^(2)`

so

`90=xy` -----> equation A

`x=4y-9` -----> equation B

substitute equation B in equation A and solve for y

`90=(4y-9)y`

`4y^(2)-9y-90=0`

using a graphing calculator

The solution is

`y=6\ ft`

Find the value of x

`x=4y-9` ----->
`x=4(6)-9=15\ ft`