计算.(x+y)(x-2y)-(2y-x)(-x-2y)(a+1/2b）（a-1/2b）-（3a-3b）（3a+xb）（3x-y）（3x+y）-y（x-y）

计算:y-x分之x+y+x-y分之y-y-x分之2x-y 计算2/3x-2/x+y(x+y/3x-x-y)/x-y/x 计算：[(x+y)(x-y)-(x-y)^2+2y(x-y)]/(-2y) 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2x/x-y 计算[2x^2-(x+y)(x-y)][(-x-y)(y-x)+2y^2] 计算：x+2y/x-y+2x/y-x-3y/x-y 计算:(x-y)^2*(y-x)^2*(x-y)^6 计算(x-y)(y^2-x^2)(-x-y) 计算(x+y)(x+y)^2(-x-y)^3 3x(x-y)+2y(x-y) 计算 计算：（x-y）^2-(x+y)(x-y) （x-2y）(x+y)+（x+y）计算 计算(2x+y)(x-y)-(2x+y)(y-2x)+(2x^2y-y)^2/(-y^2)