3x²y-{2x²y-3(2xy-x²y-x²y)-xy}
急![(3x+y)²-3(3x-y)(x+y)-(x-3y)(x+3y)]÷(2xy)
计算3x[xy-2x(1/y-x/3]+3y(x²-y²)
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
x²/xy-x/y
x-y/x²÷x²-2xy+y²/xy*(xy-x²)
计算:(xy-x²)×x-y/xy
(x+3y)(x-y)-(x+y)^2 =x²-xy+3xy-3y²-x²-y²
计算 2xy[4x²y²-3y(xy+x²y)-xy²]
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
计算:x²+2xy+y²/xy-y².x²-2xy+y²/xy+y