x^4 - 16
x^2 + 6x +9
3x^2 + 9x
x^2 + 8x + 16
25x^2 - 49
5x+ 5
20x + 10
(x + 4)^2
(5x + 7)(5x - 7)
3x(x+3)
(x^2 + 4)(x +2)(x - 2)
10(2x + 1)
5(x + 1)
(x + 3)^2
