Question

先化简,再求值:(x^2-y^2/xy)÷(x+y)乘(x/x-y)^3,其中x=-1/2,y=-1

Answer 1

((x+y)(x-y)/xy)÷（x+y）乘（x³/(x-y)³)
=((x-y)/xy）×（x³/(x-y)³)
=x²/(x-y)²y
代值：（-1/2）²/(-1)²(-1)
=(1/4)/(-1)
=-1/4
希望能帮到你

追问

应该等于-1.。 不过还是谢谢你。

追答

唉，惭愧啊

Answer 2

[(x²-y²)/(xy)]÷(x+y)×[x/(x-y)]³
=[(x-y)/(xy)]×x³/(x-y)³
=x²/[y×(x-y)²]
=(1/4)/{-1×[(-1/2)-(-1)]²}
=-1