原式=[(x-1)/(x+1) +2x/(x²-1)]÷1/(x²-1)
=[(x-1)/(x+1) +2x/(x²-1)]×(x²-1)
=(x²-1)×(x-1)/(x+1) +(x²-1)×2x/(x²-1)
=(x-1)²+2x
=x²-2x+1+2x
=x²+1
要使代數(shù)式有意義,分母不能等于0,x+1≠0 且 x²-1≠0；所以 x≠±1
當(dāng)x=2時
原式=2²+1=4+1=5