(m+n)^2
(x+y)(x-y)
(a-b)^2
(x-y)^2
(2x-4y)(2x+4y)
(3m-3n)(3m+3n)
(x+y)^2
(a+b)^2
(a^2-b^2)(a^2+b^2)
(5a-b)^2
(a+b)(a-b)
(2m+5)(2m-5)
