1/2+1/3+1/4+1/5+.+1/n=?
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?
证明(1+2/n)^n>5-2/n(n属于N+,n>=3)
证明不等式:(1/n)^n+(2/n)^n+(3/n)^n+.+(n/n)^n
证明:1+2C(n,1)+4C(n,2)+...+2^nC(n,n)=3^n .(n∈N+)
1 + (n + 1) + n*(n + 1) + n*n + (n + 1) + 1 = 2n^2 + 3n + 3
lim 9^n+4^n+2/5^n-3^2n-1 n趋于无穷大时
化简:1/(n+1)(n+2)+1/(n+2)(n+3)+1/(n+3)(n+4)
(n+1)(n+2)/1 +(n+2)(n+3)/1 +(n+3)(n+4)/1
M=(N-1)×1+(N-2)×2+(N-3)×4+(N-4)×8+(N-5)×16+(N-6)×32+(N-7)×64
1除以(n+3)(n+4)+1除以(n+4)(n+5)+、、、1除以(n+10)(n+11)=?
一道数列求和题1/2n+3/4n+5/8n+...+(2n-1)/n*2^n
急1)C(n,0)+2C(n,1)+3C(n,2)+4C(n,3) +...+(n+1)C(n,n)=(n+2)*2^(