先化简,再求值:3x²-[2x²y-(xy²-x²y)-4xy²],其

先化简,再求值:{xy(x²-3y)+3xy²}(-2xy)+x³y²(2x-y 先化简,再求值 4（xy²＋3xy-2x²y)-[12xy-3(3x²y-2xy² 先化简,再求值.x²y²-4)（-x²y²-4)-4(xy-1/2)·(xy-1 先化简,后求值[(x-y)²-(x+y)]/(2xy) 先化简,后求值[(x-y)²-(x+y)]/ 先化简在求值(x+y)²-(x-y)(x+y)-(xy)²÷(xy),其中x,y是方程组『3x+2y 化简并求值 xy-2{xy-[3x²y-(xy²+0.5xy)]+4x²y},其中x=1, 先化简,再求值:2x²-2y²分之4x²-8xy+4y²乘xy(x-y)分之(x 化简求值：x-y/x²-2xy+y²-xy+y²/x²-y²,其中(x 先化简,再求值：3x²—[2x²y—（xy—x²）]+4x²y,其中x=—1,y 先化简,再求值:4(-xy²+3x²y-1)-3(4x²y+2xy²-x),其中 先化简在求值：(-1/3XY)²×[xy(2x-y)-2x(xy-y)²],其中X=-3/2,Y=2 先化简在求值：(-1/3XY)²×[xy(2x-y)-2x(xy-y)²],其中X=-3/2,Y=-