(1/2+1/3+1/4+1/5....+1/60)+(2/3+2/4+2/5....+2/60)+(3/4+3/5+3/6+.....+(58/59+58/60)+59/60)
来源:百度知道 编辑:UC知道 时间:2024/06/09 10:16:45
(1/2+1/3+1/4+1/5....+1/60)+(2/3+2/4+2/5....+2/60)+(3/4+3/5+3/6+.....+(58/59+58/60)+59/60)
=1/2+(1+2)/3+(1+2+3)/4+...+(1+2+...+59)/60
第n项为:
(1+2+。。。+n)/(n+1)
=n(n+1)/2(n+1)
=n/2
原式=(1+2+3+...+59)/2
=(1+59)59/2/2
=885
建立数列
an=(1+2+...+(n-1))/n=(n-1)/2
原式=a2+a3+...+a60
=(1+2+3+...+59)/2
=60*59/4
=885
肯定对!!!!!!!!
(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+1/2+1/3+.....+1/n
1+1/2+1/3+...+1/100
1-1/2+1/3-.....-1/10
(1+1/2+1/3+1/4)×
1+1/1+2+1/1+2+3+...+1/1+2+3...+2000
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)