1. a (x-4) (y+3) + b (4-x )(3+y) = (x-4) (y+3) ( )
2. 将 x (x+y) (x-y) - x (x+y)^2 分解因式得________________
3. (x+y)^3 - y(x+y)^2 + x^2(y+x) = ( ) (2x+y)
4. -35x (x+y) - 42 (x+y) = ( ) (x+y) ( )
将下列各式因式分解
5. m(a-b)(x+y) - n(b-a)(y+x)
6. x(x-y-z) + y(z-x+y) - z(y-x+z)