（1）（x-y）²-2²（2）3a²bx四次方-48a²b（3）x八次方-y八次

(1) = (x - y +2)(x - y - 2) = x^2 - xy - 2x - xy + y^2 + 2y + 2x - 2y - 4 = x^2 + y^2 - 2xy - 4
(2) = 3*a^2* b* x^4 - 48*a^2*b = a^2*b(3x - 48)
(3) = x^8 - y^8 = (x^4 + y^4)(x^4 - y^4) = (x^4 + y^4)(x^2 + y^2)(x^2 - y^2) = (x^4 + y^4)(x^2 + y^2)(x + y)(x - y)