UC知道1/3+1/9+1/27+~~~~~~~~~+1/3的2006次方
来源：百度知道 编辑：UC知道 时间：2024/06/15 12:36:45
要详细
就是等比数列
sn=(a1-anq)/(1-q)
=1/3-1/3^2006* 1/3 / (2/3)
=2-2*(1/3)^2006
设S=1/3+1/9+1/27+~~~~~~~~~+1/3的2006次方
3S=1+1/3+1/9+1/27+......+1/3^2005
3S-S=2S=1-1/(3^2006)
S[1-1/(3^2006)]/2
1/3+1/9+1/27+~~~~~~~~~+1/3的2006次方
=(3^2005+3^2004+3^2004+………+1)/3^2006
=(1(1-3^2006)/(1-3))/3^2006
=(3^2006-1)/(3^2006)*2
1/1*2+1/2*3+1/3*4+......+1/9*10
9/1=3/X-6/1
1+3/1+9/1+27/1+81/1+...
1/3+1/9+1/27+...+1/3 50
1/3+1/5+1/7+1/9+1/11..+1/99
1/3+1/5+1/7+1/9+1/11+ ...............+1/2001=?
1/3+1/5+1/7+1/9+1/11+...1/99=?
1/3+1/6+1/9+1/12+1/15-1/18
1/3*1+1/5*3+1/7*5+1/9*7+.....1/2007*2005
1/1*3+1/2*4+1/3*5+1/4*6+...+1/9*11