Tr , cou đợi chút tớ đang làm b3 đây ạ

`1)c)` `2` phân số tối giản : `1/5 ; 12/35`

`2` phân số chưa tối giản : `2/6 ; 14/35`

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`2)a) -3/8 + 1/4`

`= -3/8 + 2/8`

`= -1/8`

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`b) 12/13 + (2021/2023 - 12/13)`

`=12/13 + 2021/2023 - 12/13`

`=(12/13-12/13)+2021/2023`

`=0+2021/2023`

`=2021/2023`

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`c)5 3/7 - ( 2 2/9 - 5 3/7 )`

`=38/7 - (20/9 - 38/7)`

`=38/7 - 20/9 + 38/7`

`=76/7-20/9`

`=684/63-140/63`

`=544/63`

`=5 3/7 - 2 2/9 + 5 3/7`

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`d)3 2/11 + 13/17 - (2 2/11 - 13/17 )`

`= 35/11 + 13/17 - ( 24/11 - 13/17 )`

`= 35/11 + 13/17 - 24/11 + 13/17`

`= 35/24 - 24/11 + 13/17 + 13/17`

`= 1 + 26/17`

`= 17/17 + 26/17`

`= 43/17`

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`g)-7/2023 . 33/25 - 8/25 . 7/(-2023)`

`=-7/2023 . 33/25 - 8/25 .(-7/2023)`

`=-7/2023 . (33/25-8/25)`

`=-7/2023 . 25/25`

`=-7/2023 .1`

`=-7/2023`

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`e)10/11-4/11:4-1/8`

`=10/11-4/11 . 1/4-1/8`

`=10/11-4/44-1/8`

`=10/11-1/11-1/8`

`=9/11-1/8`

`=72/88-11/88`

`=61/88`

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`h)3/13-15/29+(-14/29)+10/13`

`=3/13-15/29-14/29+10/13`

`=(3/13+10/13)-(15/29-14/29)`

`=13/13-1/29`

`=1-1/29`

`=29/29-1/29`

`=28/29`

`1)a)19/3 = 6 1/3`

`-21/6 = -3 3/6`

`27/5 = 5 2/5`

`-41/13 = -3 5/13`

`b)2 1/5 = (2xx5+1)/5 = 11/5`

`-3 2/5 = -((3xx5+2)/5) = -17/5`

`-6 3/7 = -((6xx7+3)/7) = -45/7`

câu a rút gọn cho 4 và câu b rút gọn cho 7 ạ 

`A=1/(2xx3)+1/(3xx4)+1/(4xx5)+1/(5xx6)+1/(6xx7)+1/(7xx8)`

`=1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7+1/7-1/8`

`=1/2-1/8`

`=4/8-1/8`

`=3/8`

Vậy `A=3/8`

da kcj 

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