TÌM X : ( x ^ 2 - 9 ) ( x + 1 )= 0 ( x + 5 ) - 73 + 457

Answer

`(x^2 - 9) . (x + 1) = 0`

`=>` $\left[\begin{matrix} x^2 - 9 = 0\\ x + 1 = 0\end{matrix}\right.$

`=>` $\left[\begin{matrix} x^2 = 0 + 9\\ x = 0 - 1\end{matrix}\right.$

`=>` $\left[\begin{matrix} x^2 = 9\\ x = -1\end{matrix}\right.$

`=>` $\left[\begin{matrix} x^2 = \left(\pm \ 3\right)^2\\ x = -1\end{matrix}\right.$

`=>` $\left[\begin{matrix} x= \pm \ 3\\ x = -1\end{matrix}\right.$

Vậy `x \in {3 ; -3 ; -1}`

_________________________________

`(x + 5) - 73 = 457`

`=> x + 5 - 73 = 457`

`=> x - 68 = 457`

`=> x = 457 + 68`

`=> x = 525`

Vậy `x = 525`