口袋妖怪黑2冰精灵:1/2+1/(2×3)+1/(3×4)……1/(2004×2005)怎么做

来源：百度文库 编辑：查人人中国名人网 时间：2024/04/25 00:57:44
用平方差公式.

1/2+1/(2×3)+1/(3×4)……1/(2004×2005)
=1-1/2+1/2-1/3……+1/2004-1/2005
=1-1/2005
=2004/2005

这里用不上平方差公式！
1/2+1/(2×3)+1/(3×4)……1/(2004×2005)
=1-1/2+1/2-1/3……+1/2004-1/2005
=1-1/2005
=2004/2005

1/2+1/(2×3)+1/(3×4)……1/(2004×2005)

=1/2+1/2-1/3+1/3-1/4+.....+1/2004-1/2005
=1/2+1/2-1/2005
=1-1/2005
=2004/2005

=(1-1/2)+(1/2-1/3)+(1/3-1/4).......-1/2005
=1-1/2005
=2004/2005

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+......+10 3/2=2+1/1*2=1/1+1/2 (1-1/2^2)(1-1/3^2)....(1-1/10^2) (1-1/2^2)(1-1/3^2)....(1-1/10^2) (1/2005-1)(1/2004-1)........(1/3-1)(1/2-1) 1/1*2+1/2*3+1/3*4+...+1/2000*2001 1/(1*2)+1/(2*3)+1/(3*4)+..+1/(99*100) 1/1+1/2+1/3+1/4+。。。。+1/N 是多少 1/2,3/2,1/5,-1/8,-2/13,(?)