计算(3xy-2x²+1/2y²)(3xy+2x²-1/2y²)
计算 2xy[4x²y²-3y(xy+x²y)-xy²]
计算:(-7x²y)(2x²y-3xy³+xy)
计算3x[xy-2x(1/y-x/3]+3y(x²-y²)
计算(1)3x/8y×16y²/27x² (2)(2xy-x²)÷x-2y/xy 2x-6
计算;(xy-x²)÷x²-2xy+y²/xy · x-y/x²
计算:x²y-(2xy²-5x²y)+3xy²-y³
3x²y+xy²-[2xy²-4x²y+(x²y-2xy²)
x-y/x²÷x²-2xy+y²/xy*(xy-x²)
计算(2x³-3x²y-2xy²)-(x³-2xy²+y³)
计算3xy[2xy-x(y-2)+x-1]
计算:3xy[2xy-x(y-2)+x]
合并同类项并计算 -3[y-(3x²-3xy)]-[y+2(4x²-4xy)]其中,x=3,y=1/