Разложите на множители:

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

2) a^3+a^2b-ab^2-b^3=

3) m^2+2mn+n^2-mb-nb=

4) xc-yc-x^2+2xy-y^2=

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

2) a^3+a^2b-ab^2-b^3 = (a-b) (a^2+b^2+ab) + ab (a-b) = (a-b) (a^2+b^2+ab+ab) = (a-b) (a^2+b^2+2ab)

3) m^2+2mn+n^2-mb-nb = (m+n) ^2-b (m+n) = (m+n) (m+n-b)

4) xc-yc-x^2+2xy-y^2=c (x-y) - (x-y) ^2 = (x-y) (c-x+y)