已知1^+2^2+3^2+…+n^2=1/6n(n+1)(2n+1)求1^2+3^2+5^2+…+99^2今晚就要过程谢
已知1^+2^2+3^2+…+n^2=1/6n(n+1)(2n+1)求1^2+3^2+5^2+…+99^2今晚就要过程谢
证明不等式:(1/n)^n+(2/n)^n+(3/n)^n+.+(n/n)^n
已知Sn=2+5n+8n^2+…+(3n-1)n^n-1(n∈N*)求Sn
求极限Xn=n/(n^2+1)+n/(n^2+2)+n/(n^2+3)+……+n/(n^2+n),
[3n(n+1)+n(n+1)(2n+1)]/6+n(n+2)化简
(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
2^n/n*(n+1)
证明(1+2/n)^n>5-2/n(n属于N+,n>=3)
1\n(n+3)+1\(n+3)(n+6)+1\(n+6)(n+9)=1\2 n+18 n为正整数,求n的值
已知an=5n(n+1)(n+2)(n+3),求数列{an}的前n项和Sn
已知1/n^2+3n=A/n+B/n+3,求ab?
Sn=n(n+2)(n+4)的分项等于1/6[n(n+2)(n+4)(n+5)-(n-1)n(n+2)(n+4)]吗?