1/2 + 1/6 + 1/12 + 1/20 + 1/30 Các bạn giải chi tiết giúp mình nha. 19/07/2021 Bởi Reese 1/2 + 1/6 + 1/12 + 1/20 + 1/30 Các bạn giải chi tiết giúp mình nha.
`1/2 + 1/6 + 1/12 + 1/20 + 1/30` Ta có: `1/2 = 1 – 1/2` `1/6 = 1/2 – 1/3` `1/12 = 1/3 – 1/4` `1/20 = 1/4 – 1/5` `1/30 = 1/5 – 1/6` `⇒ 1/2 + 1/6 + 1/12 + 1/20 + 1/30= 1 – 1/2 + 1/2 – 1/3 + 1/3 – 1/4 + 1/4 – 1/5 + 1/5 – 1/6` `= 1 – (-1/2 + 1/2) + (-1/3 + 1/3) + (-1/4 + 1/4) + (-1/5 + 1/5) + -1/6` `= 1 – 1/6` `= 6/6 – 1/6` `= 5/6` Bình luận
`1/2`+`1/6` + `1/12` + `1/20` + `1/30` =`1/2`+`1/2.3`+`1/3.4`+`1/4.5`+`1/5.6` =`1/2`+`1/2` – `1/3` + `1/3` – `1/4` + `1/4` – `1/5` + `1/5` – `1/6` =`1/2`+`1/2`-`1/6`=`1`-`1/6`=`5/6` `Đáp` `án`:`5/6` Chúc bạn hok tốt❤ @kiwi0978 Xin hay nhất+5 sao ạ! Bình luận
`1/2 + 1/6 + 1/12 + 1/20 + 1/30`
Ta có: `1/2 = 1 – 1/2`
`1/6 = 1/2 – 1/3`
`1/12 = 1/3 – 1/4`
`1/20 = 1/4 – 1/5`
`1/30 = 1/5 – 1/6`
`⇒ 1/2 + 1/6 + 1/12 + 1/20 + 1/30= 1 – 1/2 + 1/2 – 1/3 + 1/3 – 1/4 + 1/4 – 1/5 + 1/5 – 1/6`
`= 1 – (-1/2 + 1/2) + (-1/3 + 1/3) + (-1/4 + 1/4) + (-1/5 + 1/5) + -1/6`
`= 1 – 1/6`
`= 6/6 – 1/6`
`= 5/6`
`1/2`+`1/6` + `1/12` + `1/20` + `1/30`
=`1/2`+`1/2.3`+`1/3.4`+`1/4.5`+`1/5.6`
=`1/2`+`1/2` – `1/3` + `1/3` – `1/4` + `1/4` – `1/5` + `1/5` – `1/6`
=`1/2`+`1/2`-`1/6`=`1`-`1/6`=`5/6`
`Đáp` `án`:`5/6`
Chúc bạn hok tốt❤
@kiwi0978
Xin hay nhất+5 sao ạ!