求1+11+2+11+2+3+11+2+3+4+…+11+2+3+…+n,(n∈N
用数学归纳法证明:1×2×3+2×3×4+…+n×(n+1)×(n+2)=n(n+1)(n+2)(n+3)4(n∈N
求极限Xn=n/(n^2+1)+n/(n^2+2)+n/(n^2+3)+……+n/(n^2+n),
证明不等式:(1/n)^n+(2/n)^n+(3/n)^n+.+(n/n)^n
(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
f(n)=1/(n+1) + 1/(n+2) + 1/(n+3) + …… + 1/(2n),(n∈整数,且n≥2),求
已知Sn=2+5n+8n^2+…+(3n-1)n^n-1(n∈N*)求Sn
求极限lim(1/2n+3/4n+……+(2^n-1)/(2^n*n))
lim(1/n^2+4/n^2+7/n^2+…+3n-1/n^2)
求极限 lim(n->无穷)[(3n^2-2)/(3n^2+4)]^[n(n+1)]
求lim(n+1)(n+2)(n+3)/(n^4+n^2+1)
若n为正整数,求1/n(n+1)+1/(n+1)(n+2)+1/(n+2)(n+3)+1/(n+3)(n+4)+.+1/
证明:1+2C(n,1)+4C(n,2)+...+2^nC(n,n)=3^n .(n∈N+)