Algebra 2
posted by Lyle Eleda .
You are creating a metal border of uniform width for a wall mirror that is 20 inches by 24 inches. You have 416 square inches of metal to use. Write and solve an equation to find the border's width.

final dimensions of the framed mirror:
(20+2w) x (24+2w)
final area: (20+2w)(24+2w)
mirror area: 20*24
border area: (20+2w)(24+2w)480
= 480 + 88w + 4w^2  480 = 416
w^2 + 22w  104 = 0
(w+26)(w4) = 0
w = 4