2x²+xy-y²怎么化简

化简求值：x-y/x²-2xy+y²-xy+y²/x²-y²,其中(x 化简求值3x²y-[2xy-2（xy-3/2x²y)+xy]+3xy²其中x=3、y=-1 化简求值3x²y-[2xy²-2(xy-3/2x²y)+xy]+3xy² ,当x 化简并求值 xy-2{xy-[3x²y-(xy²+0.5xy)]+4x²y},其中x=1, 化简求值(xy-x²)/xy分之x²-2xy+y²乘x²分之x-y,其中y=二分 1.化简求值：(x+y)(x-y)-(x-y)²-6x²y÷2y+(2xy)²÷(-4xy 化简求值(x+y)(x-y)-(x-y)²-6x²y/2y+(2xy)²/(-4xy)其中 化简求值(x+y)(x-y)-(x-y)²-6x²y除2y+(2xy)²除(-4xy)其中 化简求值:(-1/3XY)²[xy(2x-y)-2x(xy-y²)],其中X=-3/2,Y=-2 化简求值：（负三分之一 xy）²[xy（2x-y）-2x（xy-y²）],其中x=-一又二分之一,y 2x+2y/x-y与(x+y)²/xy 怎么通分 化简求值[1-(2x/x+y）]÷ （x²-2xy+y²/3x+3y）+（x²+xy/x&