Question

[Lê Ngọc Đạt]

N = 1/2+1/6+1/12+1/20+1/30+1/42

Answer 1

[Akame]

N=1/1.2+1/2.3+1/3.4+1/4.5+1/5.6+1/6.7

N=1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7

N=1-1/7=6/7

Ung ho mk nhe