[x/﹙xy+y﹚]·[﹙x²+x﹚／x²y]
=[x/﹙y（x+1﹚]·[x﹙x+1﹚／x²y]
=1/y(x+1)*(x+1)/y
=1/y²
如果本题有什么不明白可以追问,