Tính nhanh: 4/3 + 16/15 + 36/35 + 64/63 + 100/99 + 144/143

Đáp án + Giải thích các bước giải :

`4/3 + 16/15 + 36/35 + ... + 144/143`

`= (1+1/3) + (1+1/15) + (1+1/35) + ... + (1+1/143)`

`= 1 + 1/3 + 1 + 1/15 + 1 + 1/35 + ... + 1+ 1/143`

`= (1+1+1 + ... +1)(6` số `1) + (1/3 + 1/15 + 1/35 + ... + 1/143)`

`= 6xx1 + (1/(1xx3) + 1/(3xx5) + 1/(5xx7)+ ... + 1/(11xx13))`

`= 6 + 1/2 xx (2/(1xx3) + 2/(3xx5) + 2/(5xx7) + ... + 2/(11xx13))`

`= 6 + 1/2 xx (1/1 - 1/3 + 1/3 - 1/5 + 1/5 - 1/7 + ... + 1/11 - 1/13)`

`= 6 + 1/2 xx (1/1 -1/13)`

`= 6 + 1/2 xx 12/13`

`= 6 + 6/13`

`= 84/13`

`#ShinHuynGun`