先化简,再求值 (xy²+3y³-x²y)—(-2x²y+y³+xy&
先化简,再求值:{xy(x²-3y)+3xy²}(-2xy)+x³y²(2x-y
先化简再求值,3xy²(xy+2y²-x²)+3x³y²,其中x=2,
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
先化简,后求值[(x-y)²-(x+y)]/(2xy) 先化简,后求值[(x-y)²-(x+y)]/
先化简,再求值:3x³y²(-3xy³)-(-x²y³)(-x
先化简,再求值 4(xy²+3xy-2x²y)-[12xy-3(3x²y-2xy²
先化简,在求值9x³-xy²/(3x+y)(9x²-6xy+y²)其中x=1,y
化简求值:x-y/x²-2xy+y²-xy+y²/x²-y²,其中(x
[-xy/(x-y)²]²×(y²-xy/x)³
先化简,再求值:3x²—[2x²y—(xy—x²)]+4x²y,其中x=—1,y
先化简在求值:(-1/3XY)²×[xy(2x-y)-2x(xy-y)²],其中X=-3/2,Y=2
先化简在求值:(-1/3XY)²×[xy(2x-y)-2x(xy-y)²],其中X=-3/2,Y=-