先化简再求值(x²-xy)-3(2x²-3xy)-2[x²-(2x²-xy+y&
先化简再求值:2x²+(-x²+3xy+2y²)-(-x²-xy+2y²
先化简再求值(x²-xy)-3(2x²-3xy)-2[x²-(2x²-xy+y&
先化简,再求值:{xy(x²-3y)+3xy²}(-2xy)+x³y²(2x-y
化简求值[1-(2x/x+y)]÷ (x²-2xy+y²/3x+3y)+(x²+xy/x&
x-y/x²÷x²-2xy+y²/xy*(xy-x²)
先化简再求值:2xy(x-3y-2)-y(2x²-6xy-3x),其中x=-3 , y=2
先化简再求值,3xy²(xy+2y²-x²)+3x³y²,其中x=2,
化简求值3x²y-[2xy-2(xy-3/2x²y)+xy]+3xy²其中x=3、y=-1
化简求值3x²y-[2xy²-2(xy-3/2x²y)+xy]+3xy² ,当x
先化简再求值(x²+xy-2y²)/(x²-2xy+y²)
化简并求值 xy-2{xy-[3x²y-(xy²+0.5xy)]+4x²y},其中x=1,
3x²y+xy²-[2xy²-4x²y+(x²y-2xy²)