奥数题:1+1/(1+2)+1/(1+2+3)+1/(1+2+3+4)+……+1/(1+2+3+4……+10)等于几?要快哦,谢谢了
奥数题:1+1/(1+2)+1/(1+2+3)+1/(1+2+3+4)+……+1/(1+2+3+4……+10)等于几?要快哦,谢谢了
日期:2011-02-11 11:07:10 人气:1
1+1/(1+2)+1/(1+2+3)+1/(1+2+3+4)+……+1/(1+2+3+4……+10)
=1/ (1*2 /2) +1/ (2*3 /2) +1/ (3*4 /2) +1/ (4*5 /2)+……+1/ (10*11 /2)
=2/ 1*2 +2/ 2*3 +2/ 3*4 +2/ 4*5 +……+ 2/ 1