Câu 1 :

` ( -2)^3 + \frac{1}{2} : \frac{1}{8} - \sqrt{25 }+|-64|`

` = -8 + \frac{1}{2} . 8 - 5+64`

` = - 8 + 4 - 5 + 64 `

` = 55`

Câu 2 :

` | 2x - 3 | - \frac{3}{4} = 4,25 `

` ⇒ | 2x - 3 | =  \frac{17}{4} + \frac{3}{4}`

` ⇒ | 2x - 3 | =5 `

` ⇒ `\(\left[ \begin{array}{l}2x - 3=5\\2x - 3=-5\end{array} \right.\) 

` ⇒ `\(\left[ \begin{array}{l}2x=8\\2x=-2\end{array} \right.\)

` ⇒ `\(\left[ \begin{array}{l}x=4\\x=-1\end{array} \right.\) 

Vậy ` x ∈ { 4 ; -1 }`

`( - 2 )^3 + 1/2 : 1/8 - sqrt{25} + | - 64 |`

`= - 8 + 1/2 × 8/1 - 5 + 64`

`= - 8 + 4 - 5 + 64`

`= - 4 + 59`

`= 55`

`| 2x - 3 | - 3/4 = 4,25`

`| 2x - 3 | = 4,25 + 3/4`

`| 2x - 3 | = 5`

`⇒ 2x - 3 = 5` `hoặc` `2x - 3 = - 5`

`⇒ 2x = 5 + 3` `hoặc` `2x = - 5 + 3`

`⇒ x = 8 : 2` `hoặc` `x = - 2 : 2`

`⇒ x = 4` `hoặc` `x = - 1`

 `Vậy` `x ∈ { 4; - 1 }`