Bài 2: (1,0 điểm): Thực hiện phép tính (tính hợp lý nếu có) a) 0,25 - $\frac{2}{3}$ + 1$\frac{1}{4}$.$\frac{8}{7}$ b) ($\frac{-3}{4}$ + $\frac{4}{15}$) : $\frac{2022}{2023}$ + ($\frac{-1}{4}$ + $\frac{11}{15}$) : $\frac{2022}{2023}$

Đáp án+Giải thích các bước giải:

 `a)`

`0,25-2/3+1 1/4. 8/7`

`=1/4-2/3+(1+1/4). 8/7`

`=1/4-2/3+8/7+ 1/4. 8/7`

`=1/4.(1+8/7)-2/3+8/7`

`=1/4.(7/7+8/7)-2/3+8/7`

`=1/4. 15/7-2/3+8/7`

`=15/28-2/3+8/7`

`=45/84-56/84+96/84`

`=85/84`

`b)`

`(\frac{-3}{4}+4/15): \frac{2022}{2023}+(\frac{-1}{4}+11/15):\frac{2022}{2023}`

`=(-3/4+4/15).\frac{2023}{2022}+(-1/4+11/15). \frac{2023}{2022}`

`=\frac{2023}{2022}.(-3/4+4/15-1/4+11/15)`

`=\frac{2023}{2022}.[-(3/4+1/4)+(4/15+11/15)]`

`=\frac{2023}{2022}.(-4/4+15/15)`

`=\frac{2023}{2022}.(1-1)`

`=\frac{2023}{2022}.0`

`=0`