计算：(x-y)^2/(x+y)÷(y-x)×1/(x-y)(m^2-4n^2)/(3mn^3)×mn/(m+2n)

计算:y×(y/x)^3÷[-(x^2)/y]^-2 计算:y-x分之x+y+x-y分之y-y-x分之2x-y 计算：(x-y)^7÷(y-x)^6+(-x-y)^3÷(x+y)^2 计算(x-y)^7÷(y-x)^6+9-x-y)^3÷(x+y)^2 [(2x+y)(x-3y)+y(x+3y)]÷(2x)计算, 计算[(x+2y)²-(x+y)(x-y)-5y²]÷(2x) 计算：[（x+y）³-2(x+y)²-4(x+y)]÷（x+y) 计算[(x+y)的立方-2(x+y)的平方-4(x+y)]÷(-x-y) 计算：[(x+y)(x-y)-(x-y)^2+2y(x-y)]/(-2y) 计算：(x+y/x-y)÷(xy+x^2) 计算:(x+2y)(2x-y) 计算:(x+3y)(2x-y) 计算:(2x-3y)(x+y) 计算:(-x-2y) * (3x-y) 计算：(x+y)-3(x-2y). 计算：(x-y)^8÷(y-x)^4×(x-y) 计算:(x-y)^2*(y-x)^2*(x-y)^6 计算(x-y)(y^2-x^2)(-x-y)