计算:3xy(x²y-xy²+xy)-xy²(2x-xy+2x)
计算:(xy-x²)×x-y/xy
计算 2xy[4x²y²-3y(xy+x²y)-xy²]
x-y/x²÷x²-2xy+y²/xy*(xy-x²)
计算:x²+2xy+y²/xy-y².x²-2xy+y²/xy+y
计算;(xy-x²)÷x²-2xy+y²/xy · x-y/x²
计算:(xy-x²)乘 x-y分之xy
计算:3xy[2xy-x(y-2)+x]
计算:(-7x²y)(2x²y-3xy³+xy)
计算:-2x²y(-2xy²)²+(2xy)³·(xy²)
(-x²+2xy-y的平方)-2(xy—3x²)+3(2y的平方-xy) 计算.
-3(xy-2x²)-[y²-(5xy-4x²)+2xy]
已知x:y=3:2,求(x²+3xy)/(xy+2xy)