为了方便，我用L代替lim(x→1)，用J代替lim(t→∞)原式=L {1+1/[(x+1)/(x-1)]}^{[(x+1)/(x-1)][(2x)/(x+1)]}设(x+1)/(x-1)=t原式=L {J [(1+1/t)^t]}^[(2x)/(x+1)]=L e^[(2x)/(x+1)]=e解题思路：此题属于1^∞类型求极限，构造第二个重要极限
