Question

一道初三的数学题。急求2小时之内解答

1 + 1/1+2 + 1/1+2+3 + …… + 1/1+2+3+4+……+n

Answer 1

解：
1 + 1/(1+2 )+ 1/(1+2+3 )+ …… + 1/(1+2+3+4+……+n)

=2[1/(1*2)+1/(2*3)+1/(3*4)+…… +1/n(1+n)]

=2[1-1/2+1/2-1/3+1/3-1/4)+…… +1/n-1/(1+n)]

=2[1-1/(1+n)]

=2-2/(1+n)

=2n/(n+1)

Answer 2

可否回答我，这条题目要我回答什么

Answer 3

拜托你把分母，分子的部分用括号括起来么，要不看到的全是 1／1

Answer 4

1/(1+2+3+4+……+n)=2/(1+n)n
1 + 1/(1+2 )+ 1/(1+2+3 )+ …… + 1/(1+2+3+4+……+n)
=2[1/(1*2)+1/(2*3)+1/(3*4)+…… +1/n(1+n)]
=2[1-1/2+1/2-1/3+1/3-1/4)+…… +1/n-1/(1+n)]
=2[1-1/(1+n)]
=2-2/(1+n)

Answer 5

原式=1+（1-1/2）+（2/3-2/4）+（2/4-2/5）+……+[2/n-2/(n+1)]=1+1/2+2/3-2/(n+1)=13/6-2(n+1)

Answer 6

我要回答什么????