先化简再求助：(-x^3+3x^2·y-y^3)-(x^3-2xy^2+y^3)+(2x^3-3x^2·y-2xy^2)

(x-2xy)*(-xy+2y*y)-(3x*x-2xy)(x-9xy+6y*y) [x(x^2y^2-xy)-y(x^2-x^3y)]/3x^2y (x+y)(x-y)-(2xy+3y)平方 1、(-7x^y)(2x^y-3xy^3+xy) 2、((x-y)^6)/((y-x)^3)/(x-y) 化简：x-y/x+3y÷x^-y^2/x^2+6xy+9y^2-(xy/x+y) (3xy)平方/(-xy)+(x-2y)平方-(x+2y)(x-2y)＝ x^2-xy-6y^2+3xy+y+2 计算3xy[2xy-x(y-2)+x-1] 计算：3xy[2xy-x（y-2）+x] （-3x^y+2xy)-( )=4x^+xy x^3y+2x^2y^3+xy^3 因式分解x^3+x^2y-xy^2-y^3