1×2+2×3+3×4+……+n（n+1）=?

1+(n+2)+(2n+3)+(3n+4)+(4n+5)+……((n-1)n+n)的答案 lim(1/n^2+4/n^2+7/n^2+…+3n-1/n^2) lim(1/n+2/n+3/n+4/n+5/n+……+n/n)=lim(1/n)+lim(2/n)+……+lim(n/n)成立吗?（n趋近于无穷大）为什么不成立? 证明不等式：(1/n)^n+(2/n)^n+(3/n)^n+.+(n/n)^n 若n等于1或-1,求n-2n+3n-4n+…+49n的值 (1/(n^2 n 1 ) 2/(n^2 n 2) 3/(n^2 n 3) ……n/(n^2 n n)) 当N越于无穷大的极限(1/(n^2+n+1 ) +2/(n^2+n+2) +3/(n^2+n+3) ……n/(n^2+n+n)) 当N越于无穷大的极限 {[(1+n)(2+n)(3+n)……(n+n)]^(1/n)}/n当趋向正无穷 求其极限 e^(1/n)+e^(2/n)+e^(3/n)+…+e^(n-1/n)+e^(n/n)=? 设f(n)=1/n+1+1/n+2+1/n+3+……+1/3n(n∈N+),则f(n+1)-f(n)=? 证明:(3^n)*(2^1/n)>(3^n)+(2^1/n)……n属于正整数 证明1/(n+1)+1/(n+2)+1/(n+3)+……+1/(n+n) lim(n+3)(4-n)/(n-1)(3-2n) lim(n^3+n)/(n^4-3n^2+1) VB编程n!+(n+1)!+(n+2)!+(n+3)!+……+(n+m)!要有控件 1+2+3+4+……+n=n(n+1)(2n+1)/6 求当n→∞,Lim(1+2+3+4+……+(n-1)+n)/n n/(n+1)!数列求和1/2!+2/3!+3/4!+…+n/(n+1)! 请解(n+1)/2n之和( n=1,2,3,4,5…n)