（7x^2-y^2)^2-(x^2-7y^2)^2

1、x(x-y)(x+y)-x(x+y)^2 (x-y)^2+7(x+y)-11(x-y)^2-8(x+y),先化简.再求值 解方程组(x+y)(x-2y)=-5 (x-y)(x+2y)=7 (-3x+7y)(-7y-3x)-(x-3y)(2x+3y) 2(y-x)的平方-7(x-y)+6(x-y)-3(y-x)的平方 若(x-y)/(x+y)=3 则(x+2y)/(6x-7y)等于 计算：(x-y)^7÷(y-x)^6+(-x-y)^3÷(x+y)^2 计算(x^8-x^7y+x^5y^3-x^4y^4+x^3y^5-x^y^7+y^8)(x^2+xy+y^2) x^8-x^7y+x^6y^2-x^5y^3+x^4y^4-x^3y^5+x^2y^-xy^7+y^8 1、(-7x^y)(2x^y-3xy^3+xy) 2、((x-y)^6)/((y-x)^3)/(x-y) 因式分解:8(x-2y)-x(7x+y)+xy. (1)(x^2/x)-y-x-y