[질문] x(x+y)-y(x+y) (x-1)a+(x-1) x(a-b)-a+b 1-x-y+xy 2a-ab-2+b ac-bd-ad+bc 식을 인수분

1.(x+y)(x-y), 2.(x-1)(a-1),3.(x-1)(a-b),4.(x-1)(y-1),5.(a-1)(2-b),6.(a+b)(c-d)입니다.