1/(n+1)+1/(n+2)+1/(n+3)+ ……+1/3n 极限

求极限Xn=n/(n^2+1)+n/(n^2+2)+n/(n^2+3)+……+n/(n^2+n), 1/(n+1)+1/(n+2)+1/(n+3)+ ……+1/3n 极限 证明不等式：(1/n)^n+(2/n)^n+(3/n)^n+.+(n/n)^n 求极限lim(1/2n+3/4n+……+(2^n-1)/(2^n*n)) 求极限 lim n[1/(n^2+1)+1/(n^2+2^2）+……+1/(n^n+n^n)] (n趋向于无穷大,n^n 求极限lim [ 2^(n+1)+3^(n+1)]/2^n+3^n (n→∞) (2^n+(-3)^n)/(2^(n+1)+(-3)^(n+1)) n趋近无穷大的极限 求极限 n趋向无穷 2^n+1 + 3^n+1/2^n+3^n [(2n+3n)/( 2n+1+3n+1)]的极限,n趋于无穷 求极限 lim【1/（n^2+n+1）+2/（n^2+n+2）+3/（n^2+n+3）+……+n 求(1^n+2^n+3^n)^1/n,n趋于无穷大的极限 lim n →∞ (1^n+3^n+2^n)^1/n,求数列极限