Question

Chứng minh

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

Answer 1

Ta có : 1-1/2+1/3-1/4+1/5-1/6

           = 1+1/2+1/3+1/4+1/5+1/6-2.(1/2+1/4+1/6)

           = 1+1/2+1/3+1/4+1/5+1/6-(1+1/2+1/3)

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

           =1/4+1/5+1/6