Question

1/2+1/3 1/2-1/3 1/3+1/4 1/3-1/4 1/4+1/5 1/4-1/5是什么规律

Answer 1

1/n+1/(n+1),1/n-1/(n+1)....(n>=2)

Answer 2

31*1/2*1/3 + 41*1/3*1/4 + 51*1/4*1/5

=(30+1)*1/2*1/3 + (40+1)*1/3*1/4 + (50+1)*1/4*1/5

=5+1/6 + 10/3+1/12 + 5/2+1/20

=300/60 + 10/60 + 200/60 + 5/60 + 150/60 + 3/60

=668/60

=167/15