1/2xy-{1/2xy-[1/3x^2y-(x^2y-xy)]+1/3x^2y}

计算3xy[2xy-x(y-2)+x-1] (x+y-2xy)(x+y-2)+(1-xy)² xy(xy+1)+(xy+3)-2(x+y+2分之一）-(x+y-1)的平方 (-3分之1xy)的平方×[xy(2x-y)-2x(xy-y的平方)] 1、(-7x^y)(2x^y-3xy^3+xy) 2、((x-y)^6)/((y-x)^3)/(x-y) 5x^2y/-1/2xy*3xy^2 y^3+xy^2+2xy+x^2-1 因式分解 1/2xy-{1/2xy-[1/3x^2y-(x^2y-xy)]+1/3x^2y} 化简!1、（x^2-xy）+xy+y^2 2、3（x^2-xy）-xy+y^2 （x+2y-3xy)-(-2x-y+xy),其中x+y=1/2,xy=-1/2 已知3/(x-y)=1/xy 求(-x-2xy+y)/ (2x+3xy-2y) 已知xy/x+y=1/2,则代数式3x-5xy+3y/-x+3xy-y=