Question

which expression represents the perimeter of the rectangle above? (3x-3)(3x-1) a.6x+2 b.12x-8 c.6x-4 d.12x+2

Answer 1

Perimeter of rectangle is calculated by taking the sum of all the sides of the rectangle. In rectangles the 2 opposite sides are equal 
length  - 3x - 1
breadth - 3x - 3
the formula used to calculate perimeter for rectangle 
perimeter = (2 x length) + (2 x breadth)
substituting length and breadth 
perimeter = {2 x (3x - 1)} + {2 x (3x - 3)}
                = 6x - 2 + 6x - 6 
                = 12x - 8
therefore correct answer is 
b.12x-8

Answer 2

{(3x-3)+(3x-1)}*2 = (6x-4)*2 = 12x-8
so b is correct.