w(w+6) = 315
since 315 = 15*21, ...
If a storm window has an area of 315 square inches, what are the dimensions if the window is 6 inches higher than it is wide (w x h)?
2 answers
Area = length x width
Length = width + 6
A = lw
l = w + 6
315 = (w+6)(w)
315 = w^2 +6w
0 = w^2 + 6w - 315
0 = (w+21)(w-15)
w+21 = 0 w - 15 = 0
w = -21 w = 15
discard the -21 because we don't measure distance in negative numbers.
w = 15
l = 21
Multiply to be sure they equal the area.
Length = width + 6
A = lw
l = w + 6
315 = (w+6)(w)
315 = w^2 +6w
0 = w^2 + 6w - 315
0 = (w+21)(w-15)
w+21 = 0 w - 15 = 0
w = -21 w = 15
discard the -21 because we don't measure distance in negative numbers.
w = 15
l = 21
Multiply to be sure they equal the area.
1 answer