`1 - 1/2 + 1/3 - 1/4 + .................. + 1/99 - 1/100`
`= (1 + 1/3 + ........... + 1/99) - (1/2 + 1/4 + ................ + 1/100)`
`= (1 + 1/2 + .......... + 1/100) - 2(1/2 + 1/4 + ................ + 1/100)`
`= 1 + 1/2 + .......... + 1/100 - 1 - 1/2 - ............... - 1/50`
`= 1/51 + 1/52 + ............ + 1/100`
`⇒ 1/51 + 1/52 + ............ + 1/100 = 1 - 1/2 + 1/3 - 1/4 + .................. + 1/99 - 1/100`
`text(Xin hay nhất)`
