先化简再求值,(x+y)²/(y²-xy)÷[一(y²+xy)/(x一y)²],
化简求值:(负三分之一 xy)²[xy(2x-y)-2x(xy-y²)],其中x=-一又二分之一,y
先化简再求值(x²+xy-2y²)/(x²-2xy+y²)
化简求值:x-y/x²-2xy+y²-xy+y²/x²-y²,其中(x
先化简,再求值:{xy(x²-3y)+3xy²}(-2xy)+x³y²(2x-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
数学:先化简再求值(x²+xy-2y²/x²-2xy+y²)-(1-xy
先化简,后求值[(x-y)²-(x+y)]/(2xy) 先化简,后求值[(x-y)²-(x+y)]/
1.化简求值:(x+y)(x-y)-(x-y)²-6x²y÷2y+(2xy)²÷(-4xy
计算:(xy-x²)×x-y/xy
x²/xy-x/y
先化简再求值:2x²+(-x²+3xy+2y²)-(-x²-xy+2y²
先化简再求值-1/2x²×(2xy²-4x²y²)-4x²y×(-xy