Đáp án + Giải thích các bước giải:
f, `1/(1 . 2) + 1/(2 . 3) + 1/(3 . 4) + ... + 1/(98 . 99) + 1/(99 . 100)`
` = 1 - 1/2 + 1/2 - 1/3 + 1/3 - 1/4 + ... + 1/98 - 1/99 + 1/99 - 1/100`
` = 1 - (1/2 - 1/2) - (1/3 - 1/3) - (1/4 - 1/4) - ... - (1/98 - 1/98) - (1/99 - 1/99) - 1/100`
` = 1 - 0 - 0 - 0 -.... - 0 - 0 - 1/100`
` = 1 - 1/100`
` = 100/100 - 1/100`
` = 99/100`
g, `11/125 - 17/18 - 5/7 + 4/9 + 17/14`
`= 11/125 + (17/14 - 5/7) - (17/18 - 4/9)`
`= 11/125 + (17/14 - 10/14) - ( 17/18 - 8/18)`
`= 11/125 + 1/2 - 1/2`
`= 11/125 + (1/2 - 1/2)`
`= 11/125 + 0`
`= 11/125`