有數學題唔識!!

C (x-y)[x^2(x^2 +xy+y^2) +y^3(x+y)] Using a and b.......

2007-07-18 16:00:10 補充：
(x^2 xy y^2)(x-y)=x^3-y^3(x-y)(x^2 xy y^2)x^2=x^2(x^3-y^3)y^3(x y)(x-y)=y^3(x^2-y^2)c)(x-y)(x^4 x^3y x^2y^2 xy^3 y^4) =x^2(x^3-y^3) y^3(x^2-y^2)=x^5-y^5

2007-07-18 16:14:04 補充：
c)(x-y)(x^4 x^3y x^2y^2 xy^3 y^4)=(x-y)[x^2(x^2 xy y^2) y^3(x y)]=x^2(x-y)(x^2 xy y^2) y^3(x y)(x-y)=x^2(x^3-y^3) y^3(x^2-y^2)=x^5-y^5a) (x y)(x^2-xy y^2)=x^3 (y-y)x^2 (y^2-y^2)x y^3=x^3 y^3b)Siamily....

(x-y)[x^2(x^2 +xy+y^2) +y^3(x+y)] ku!ku!ku!