Question

Which is not a valid way to determine the perimeter of a rectangle with side lengths of 18 inches and 22 inches?

P = 2(18) + 2(22)

P = 18 + 22 + 18 + 22

P = 2(18 + 22)

P = 2(18) + 22

Answer 1

P = 2(18) + 22

Explanation:

The formula for the perimeter for a rectangle is P = 2(l + w). Take this equation and expand to find its equivalents.

P = 2(l + w) This is P = 2(18 + 22)

P = 2l + 2w This is P = 2(18) + 2(22)

P = l + l + w + w This is P = 18 + 22 + 18 + 22

It is only P = 2(18) + 22 that is not equal to the others. It does not have the fourth side of 22.