Giải giúp emmm tất cả các câu ở c3 vs

Câu 3. a) $4x - 8y = 4(x - 2y)$ b) $2x(x + y) - 3y(x + y) = (x + y)(2x - 3y)$ c) $x^2 - 4 = (x - 2)(x + 2)$ d) $x^2 - 3x + xy - 3y = x(x - 3) + y(x - 3) = (x - 3)(x + y)$ e) $5ax - 10ay = 5a(x - 2y)$ f) $x^2 - xy + x - y = x(x - y) + 1(x - y) = (x - y)(x + 1)$ g) $2x^2 + 8x - 2y^2 + 8y = 2(x^2 + 4x - y^2 + 4y) = 2[(x^2 - y^2) + (4x + 4y)] = 2[(x - y)(x + y) + 4(x + y)] = 2(x + y)(x - y + 4)$ h) $x^2 + 4x - y^2 - 4y = (x^2 - y^2) + (4x - 4y) = (x - y)(x + y) + 4(x - y) = (x - y)(x + y + 4)$