(1+3m)(1-3m) = 1 - 9m^2(2x-1)(2x+1) = 4x^2 - 1(2x-y)(2x+y) = 4x^2 - y^2(x^2 + 2)(x^2 - 2) = x^4 - 4(y-a)^2(y+a)^2 = (y^2 - a^2)^2 = y^4 - 2y^2a^2 + a^4(a^2 - 4)(a^2 + 4) = a^4 - 16
(1+3m)(1-3m) = 1 - 9m^2
(2x-1)(2x+1) = 4x^2 - 1
(2x-y)(2x+y) = 4x^2 - y^2
(x^2 + 2)(x^2 - 2) = x^4 - 4
(y-a)^2(y+a)^2 = (y^2 - a^2)^2 = y^4 - 2y^2a^2 + a^4
(a^2 - 4)(a^2 + 4) = a^4 - 16