|5x-3|=|7-x| (ko phải căn bậc)

` | 5x - 3 | = | 7 - x | `

` ⇔ ` $\left[\begin{matrix} 5x - 3 = 7 - x \\ 5x - 3 = - ( 7 - x ) \end{matrix}\right.$

` ⇔ ` $\left[\begin{matrix} 5x + x = 7 + 3 \\ 5x - 3 = - 7 + x \end{matrix}\right.$

` ⇔ ` $\left[\begin{matrix} 6x = 10 \\ 5x - x = -7 + 3  \end{matrix}\right.$

` ⇔ ` $\left[\begin{matrix} x = 10 : 6  \\ 4x = -4 \end{matrix}\right.$

` ⇔ ` $\left[\begin{matrix} x = \dfrac{5}{3} \\ x = ( -4 ) : 4  \end{matrix}\right.$

` ⇔ ` $\left[\begin{matrix} x = \dfrac{5}{3} \\ x = -1  \end{matrix}\right.$

 Vậy ` S = { 5/3 ; -1 } `

Đáp án:

`|5x - 3| = |7 - x|`

`⇔` \(\left[ \begin{array}{l}5x - 3 = 7 - x\\5x - 3 = -7 + x\end{array} \right.\) 

`⇔` \(\left[ \begin{array}{l}5x + x = 7 + 3\\5x - x = -7 + 3\end{array} \right.\) 

`⇔` \(\left[ \begin{array}{l}6x = 10\\4x = -4\end{array} \right.\) 

`⇔` \(\left[ \begin{array}{l}x = \dfrac{5}{3}\\x = -1\end{array} \right.\) 

Vậy `x ∈ { 5/3 ; -1 }`

$#dariana$