原式=[(a-1)²/(a+1)(a-1)+1/a]×(a+1)
=[(a-1)/(a+1)+1/a]×(a+1)
=(a-1)/(a+1)×(a+1)+1/a×(a+1)
=a-1+(a+1)/a
=(a²-a+a+1)/a
=(a²+1)/a
令x=10
原式=(100+1)/10=101/10x哪儿来的为啥是x=10哦，对不起是令a=10