x-1:2=8:x-1 giúp vs ạ 5 sao

`(x - 1)/2 = 8/(x - 1)`

`=> (x - 1) . (x - 1) = 2 . 8`

`=> (x - 1)^2 = 16`

`=> (x - 1)^2 = 4^2 = (-4)^2`

`=> (x - 1) = +-4`

`=>` $\left[\begin{matrix} x - 1 = 4\\ x-1=-4\end{matrix}\right.$

`=>` $\left[\begin{matrix} x = 4 + 1\\ x = -4 + 1\end{matrix}\right.$

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

Vậy `x in {-3 ; 5}`

`@Sun`