Question

Jack is making a rectangular flag in art class. He has created the main part of the flag, which measures 2 feet by 1 foot. He wants to use exactly 10 square feet of material to create the flag's border. Which equation can he use to find the required width of the border, x?

Answer 1

Hello,

The flag inside has an area of 2 (ft²)

Let's assume x the width of the border.

Area of the border is:

(2+2x)(2+2x)-2=10
==> 4x²+6x-10=0
==>2x²+3x-5=0
Δ=3²+4*2*5=49=7²
x=(-3+7)/4=1 or x=(-3-7)/4=-5/2 (to exclude since <0)

The border is 1 foot wide.