[질문] 인수분해기초문제몇개만요

a²-4a+4-b²//4x²-y²+4x+1//ax+ay+2bx²+4bxy+2by²//(a+b)(x²-y²)-(x-y)(a²-b²)//x⁴-1//x⁴-y⁴//a(x-y)-b(y-x)// ab-cd+bc-ad//1-m-n+mn//열공하세요