A rectangle has side lengths (x + 4) feet and (2x - 2) feet. Write a linear expression in simplest form to represent the perimeter. Find the perimeter if the value of x is 7 feets.
Linear expression: 2(x + 4) + 2(2x - 2)
Perimeter: 2(7 + 4) + 2(2(7) - 2) = 28 + 20 = 48 feet
Nope!!
linear expression = 2(x+4) + 2(2x-2)
= 6x + 4
so when x = 7,
perimeter = 42 + 4 = 46 , not 48 !!