làm giúp em câu 1 ý a,b,c ạ

Đáp án:

Giải thích các bước giải:

 Câu `1` :

`A)`

` A = 0,75 + 2/5 + ( 1/9 - 1 2/5 + 5/4 ) - ( 1/9 + 1 ) `

` A = 3/4 + 2/5 + 19/- 7/5 + 5/4 - 1/9 - 1 `

` A = ( 1/9 - 1/9 ) + ( 3/4 + 5/4 ) + ( 2/5 - 7/5 ) - 1 `

` A = 0 + 2 - 1 - 1 `

` A = 2 - 1 - 1 `

` A = 1 - 1 `

` A = 0 `

* Vậy `A = 0`

``

`B)`

`B =  3/4 . 5/9 + 6/7 : 4/3 - 1 2/5 : 1 1/3 `

`B = 3/4 . 5/9 + 6/7 . 3/4 - 7/5 : 4/3 `

`B = 3/4 . 5/9 + 6/7 . 3/4 - 7/5 . 3/4 `

`B = 3/4 . ( 5/9 + 6/7 - 7/5 ) `

`B = 3/4 . 4/315 `

`B = 12/1260 `

`B = 1/105` 

* Vậy ` B = 1/105 `

``

`C)`

` C = (2/3 + 2/7 - 1/14)/(- 1 - 3/7 + 3/28) `

` C = (2/3 + 2/7 - 2/28)/(- 3/3 - 3/7 + 3/28) `

` C = (2 ( 1/3 + 1/7 - 1/28))/(- 3 ( 1/3 + 1/7 - 3/28)) `

` C = - 2/3 `

* Vậy ` C = - 2/3 ` 

``

`D)`

`D = (3 + 3/13 + 3/169 + 3/91)/(7 + 7/13 + 7/169 + 7/91) `

`D = (3 ( 1/13 + 1/169 + 1/91 ))/(7 ( 1/13 + 1/169 + 1/91 )) `

`D = 3/7 `

* Vậy ` D = 3/7 `