1)3(x-y)-xy(x-y)=(x-y)(3-xy)
2)a^2(a+1)-ab(a+1)=a(a-b)(a+1)
1) 3х+хy^2-x^2y-3y = 3(x-y) + xy(x-y) = (x-y)(3 + xy)
2) a^3-ab-a^2b+a^2 = a^2(a+1) - ab(1+a) = (a+1)(a^2 - ab)
