[(n+x)/(n-1)]^n ={[1+ (1+x)/(n-1)]^(n-1)/(1+x)}^[(1+x)*n/(n-1)] 所以极限是 e^(1+x){[1+ (n+1)/n²]^[n²/(n+1)]}^[n*(n+1)/n²]所以极限是 e
