Explanation:
In order to find the perimeter of a rectangle you need to add up all of the sides or in other terms (length x 2) + (width x 2).
So to do this problem you would take the given measurements and do that with them.
(5x^2 + 4x - 4)2 + (3x^2 + 2x + 6)2
Distribute the 2 to all of the terms in the equations:
(10x^2 + 8x - 8) + (6x^2 + 4x +12)
Then add them up:
16x^2 + 12x + 4