posted by Unknown .
The variable W represents the width of a rectangle. The length of the rectangle, L, is 5 less than twice the width.
Write an expression for the length of the rectangle in terms of W.
Write a simplified expression for the perimeter of the rectangle in terms of W.
Find the perimeter of the rectangle if the width is 3 inches.
Well W = 3
L = (2W)-5 = (6) - 5 = 1
W + W + L + L = perimeter
so 2W + 2L = perimeter
so subbing 2W-5 in for L we get
2W + 2(2W-5) = perimeter
= 2W + 4W-10 = perimeter
= 6W - 10 = perimeter
= 6(3) - 10 = perimeter
=18 - 10 = perimeter
= 8 = perimeter
or solving the other way L = 1 W = 3
2W + 2L = 6 + 2 = 8 = perimeter