Помогите разложить на множители многочлен:

1) ab - 8a - bx+8x

2) ax - b + bx - a

3) ax - y + x - ay

4) ax - 2bx + ay - 2by

1) ab - 8a - bx + 8x = a (b - 8) - x (b - 8) = (b - 8) (a - x)

2) ax - b + bx - a = ax + bx - (a + b) = x (a + b) - (a + b) = (a + b) (x - 1)

3) ax - y + x - ay = (ax - ay) - (x - y) = a (x - y) - (x - y) = (x - y) (a - 1)

4) ax - 2bx + ay - 2by = (ax + ay) - (2bx + 2by) = a (x + y) - 2b (x + y) =

= (x + y) (a - 2b)