(5x²-3y²)-[(5x²-2xy-y²)-(x²-2xy-y&#

-3(xy-2x²)-[y²-(5xy-4x²)+2xy] 化简（3X²-XY+Y²）-5(X²-XY+2Y²） x-y/x²÷x²-2xy+y²/xy*（xy-x²） 1/x+1/y=5,求2x-3xy+2y/x²+xy+y的值 x²/xy-x/y 计算：(xy-x²)×x-y/xy 计算：x²+2xy+y²/xy-y².x²-2xy+y²/xy+y&# 3x²y+xy²-[2xy²-4x²y+（x²y-2xy²） (2x²y-3xy²)-3(x²y-2xy²)+2（x²y-4xy&# 先化简,再求值:{xy(x²-3y)+3xy²}(-2xy)+x³y²(2x-y 已知x+y=3 xy=-5 求x设abc=1 求x²+3xy+2y²/x²y+2xy
计算:x²y-（2xy²-5x²y）+3xy²-y³