x=-1 lim=1，大于-1 lim=无穷，小于-1 lim=0
(n+x)/(n-1)=1+(x+1)/(n-1)所以不妨设1/a=(x+1)/(n-1)n=(x+1)a+1所以原式=lim(a→∞)(1+1/a)^[(x+1)a+1]=lim(a→∞)(1+1/a)^(x+1)a*(1+1/a)=lim(a→∞)[(1+1/a)^a]^(x+1)*1=e^(x+1)
