用简便的方法计算:1/(1*2)+1/(2*3)+1/(3*4)+.....+1/(99*100)
来源:百度知道 编辑:UC知道 时间:2024/05/20 12:29:09
原式=1-1/2+1/2-1/3+1/3-1/4+……+1/99-1/100
=1-1/100
=99/100
注意观察分母
1/2=1/(1*2)=1-1/2
1/6=1/(2*3)=1/2-1/3
.....
1/[n*(n+1)]=1/n-1/(n+1)
所以原式=1-1/2+1/2-1/3+1/3-1/4+.....-1/100=1-1/100=99/100 (其它的全抵消了)
1/n*(n+1)=1/n-1/(n+1)
所以原式=1/1-1/2+1/2-1/3+1/3-1/4+……+1/98-1/99+1/99-1/100
=1-1/100
=99/100
=0.99
99/100
1/(1*2)=1-1/2
1/(2*3)=1/2-1/3
1/(3*4)=1/3-1/4
1/(99*100)=1/99-1/100
所以和=99/100
*是乘号吗
原式=(1-1/2)+(1/2-1/3)+(1/3-1/4)+......+(1/99+1/100)
=1-1/2+1/2-1/3+1/3-1/4+......+1/99-1/100
=1-1/100
=99/100
就这样喽
很简单的
首先弄清楚 1/[x*(x+1)]=1/x-1/(1+x)
1/(1*2)+1/(2*3)+1/(3*4)+.....+1/(99*100)
=1-1/2+1/2-1/3+1/3-1/4+.....1/99-1/100
=1-1/100=99/100