1/(1*3)+1/(3*5)``````1/(99*101)
来源:百度知道 编辑:UC知道 时间:2024/05/31 12:46:12
奥数题,要有过程
分解2=3-1=5-3=7-5=…=101-99
所以 1/1*3+1/3*5+1/5*7+…+1/99*101
=1/2(2/1*3+2/3*5++…+2/99*101)
=1/2(1-1/3+1/3-1/5+1/5-1/7+...+1/99-1/101)
=1/2(1-1/101)
=100/202
1/1*3+1/3*5+1/5*7+…+1/99*101
=1/2(2/1*3+2/3*5++…+2/99*101)
=1/2(1-1/3+1/3-1/5+1/5-1/7+...+1/99-1/101)
=1/2(1-1/101)
=100/202
裂项相消
1/1*3+1/3*5+1/5*7+…+1/99*101
=1/2(2/1*3+2/3*5++…+2/99*101)
=1/2(1-1/3+1/3-1/5+1/5-1/7+...+1/99-1/101)
=1/2(1-1/101)
=100/202
1/1*3+1/3*5+1/5*7+…+1/99*101
=1/2(1-1/3+1/3-1/5+1/5-1/7+...+1/99-1/101)
=1/2(1-1/101)
=100/202
http://zhidao.baidu.com/question/9392370.html?fr=qrl3
很简单的裂项,要学会方法哦!
(1/2005-1)(1/2004-1)........(1/3-1)(1/2-1)
(1-1/100)(1-1/99)(1-1/98)......(1-1/3
(1-1/2)(1-1/3)(1-1/4)(1-1/5).....(1-1/1000)
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+1/2+1+1/3+1+1/4+......+1/100=?
1+1/2+1/3+.....+1/n
1+1/2+1/3+...+1/100
1+1/3+1/6+........+1/55
1-1/2+1/3-.....-1/10