1+1/(1+2)+1/(1+2+3)+1/(1+2+3+4)+...+1/(1+2+3+...+2006)急
来源:百度知道 编辑:UC知道 时间:2024/05/30 01:38:36
1+1/(1+2)+1/(1+2+3)+1/(1+2+3+4)+...+1/(1+2+3+...+2006)
因为:
1+2=2*3/2
1+2+3=3*4/2
1+2+3+4=4*5/2
1+2+3+……+2006=2006*2007/2
所以,
1+1/(1+2)+1/(1+2+3)+1/(1+2+3+4)+...+1/(1+2+3+...+2006)
=1+2/(2*3)+2/(3*4)+2/(4*5)+……+2/(2006*2007)
=2[(1/2+1/(2*3)+1/(3*4)+1/(4*5)+……+1/(2006*2007)〕
因为:
1/(2*3)=1/2-1/3;
1/(3*4)=1/3-1/4;
1/(4*5)=1/4-1/5;
……
1/(2006*2007)=1/2006-1/2007
所以,
原式=2(1/2+1/2-1/3+1/3-1/4+1/4-1/5+……+1/2006-1/2007)
=2(1-1/2007)
=2*2006/2007
=4012/2007
(1/2005-1)(1/2004-1)........(1/3-1)(1/2-1)
1+1/(1+2)+1/(1+2+3)+...+1/(1+2+3+...+100)
1+1/(1+2)+1/(1+2+3)+-------+1/(1+2+3+----+100)
1+1/1+2+1/1+2+3+...+1/1+2+3...+2000
1+1/1+2+1/1+2+3.........+1/1+2+3.....100
1*(1/1+2)*(1/1+2+3)*~~~*(1/1+2+~~~2005)=?
(1-1/2)(1-1/3)(1-1/4)(1-1/5).....(1-1/1000)
1+1/2+1+1/3+1+1/4+......+1/100=?
(1+1/2)(1+1/2^2)(1+1/2^4)(1+1/2^8)
(1-1/2^2)*(1-1/3^2)*(1-1/4^2).......(1-1/100^2)