49x^2 + 16 - 56x
ax - 2bx - 2ay + 4by
64a^2 + 9b^2 - 48ab
am-bm+an-bn
52 + x^2 + 17x
(7x - 4)2
(x -2y) (a- 2b)
(a-b)(m+n)
(4x + 4 )
(8a - 3b)^2
(x + ) (x - )