(3ax-1)(3ax+1)
(m-n)(m+n)
(x+y)(x-y)
(2a-1)(2a+1)
(2m+9)(2m-9)
(a3-b2)(a3-b2)
9a2x2 - 1
x2-y2
a9+b4
m2-n2
4a2-1
4m2-81
