计算：(1/4x^2-xy+y^2)/(x-2y)

计算3xy[2xy-x(y-2)+x-1] 计算:2xy/(x+y)².(x+y)/4y （x^2+xy/x-y)/（xy/x-y)计算 计算2(-x^4 y)²×(-1/4xy³) 计算:(x-2y)(1+x+2y+4y^2+2xy+x^2) 计算：[(x-y)^2-(x+y)^2]/(-4xy)= 计算:(4xy(x-y)^-1+(x(y^-1)-(x^-1)y)/((x^-1)+(y^-1)))*(x+y)^-2 x-y/xy-y^2计算 计算:4xy-(x+y)^2/xy(x+y)(x-y)÷x^2+xy-2y^2/x^2y+2xy^2 计算：（1）8x^2y^2*(-3x/4y^5) (2)(x+y)^2/xy-y^2*(y-x)^2/xy+y^2 计算：5xy^2-[3xy^2-(4xy^2-2x^2y)]+2x^2y-xy^2 计算x²-x/x²×x/1-x和x²-4y²/x²+2xy+y²÷x+2y/x²+xy 计算(-xy)(x+2x²y) 计算：(5-xy/x^3-x^2y)/(1-5/xy)^2*(y-x)^3 (-1/2x^3-3/2xy+1/4y^2)(-2xy^2)^2计算 计算（xy-y^2)÷x-y/xy 计算1-(x-2y/x+2y)/(x^2-y^2/4xy-x^2-4y^2) 计算 (-x^2+3xy-1/2y^2)-(-1/2x^2+4xy-3/2y^2) 谢计算(-x^2+3xy-1/2y^2)-(-1/2x^2+4xy-3/2y^2)