求证:(x^2-xy+y^2)^3+(x^2+xy+y^2)^3能被2x^2+2y^2整除

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