(-x^2+3xy-1/2y^2)-(1/2x^2+4xy-3/2y^2)=-1/2x^2+*+y^2,其中*为未知的一个字母或数字.求*和最后结果可以说说你计算的过程么？

计算3xy[2xy-x(y-2)+x-1] xy(xy+1)+xy+3-2(x+y+1/2)-(x+y-1)^2因式分解 (-1/3xy)^2•[xy(2x-y)-2x(xy-y^2)] (-3分之1xy)的平方×[xy(2x-y)-2x(xy-y的平方)] XY(XY+3)+(XY+4)+4(X+Y+1)-(X+Y+2) 若1/x-1/y=2,求3x-2xy-3y/x-xy-y的值3x-2xy-3y/x-xy-y 不好意思，是3x-2xy-3y/x-2xy-y .(x+y-2)(x+y-2xy)+(xy-1)^2 因式分解x^2y^2+x^2y+xy^2+3xy+x+y+1 1、(-7x^y)(2x^y-3xy^3+xy) 2、((x-y)^6)/((y-x)^3)/(x-y) (-xy^-1)^2*(-xy^-2)^-3/(-x^2y^3) y^3+xy^2+2xy+x^2-1 因式分解 5x^2y/-1/2xy*3xy^2 ( )-(x^2+3xy)=-xy-1/3y^2 5xy^2-{2x^y-[3xy^2-（xy^2-2x^2y）]/（-1/2xy）} 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=