Разложите на множители: 1)a^2-b^2-a+b 2)x^3-x^2y-xy^2+y^3

#1
a^2 - b^2 - a + b = (a - b)(a + b) - 1(a - b) = (a - b) (a + b - 1)

#2
x^3 - x^2y - xy^2 + y^3 = x^2 (x - y) - y^2 (x - y) = (x - y)(x^2 - y^2) = 
= (x - y)(x + y)(x - y)