Question

The area of a rectangular computer screen is 4x^2+20x+16. The width of the screen is 2x+8. What is the length of the screen?

Answer 1

So the area of a rectangle is Length x Width. 
A = (L)(W)
Substitute the information given:
4x^2 + 20x + 16 = (L)(2x+8)
Isolate L by dividing 2x+8:
(4x^2 + 20x +16)/ (2x + 8) = L
If you divide: 
L = 2x + 2.