Tìm x biết (x - 1}/{x - 5} < 0
Giải thích
\(\frac{{x - 1}}{{x - 5}} < 0\)
⇔ \[\left[ \begin{array}{l}\left\{ \begin{array}{l}x - 1 < 0\\x - 5 > 0\end{array} \right.\\\left\{ \begin{array}{l}x - 1 > 0\\x - 5 < 0\end{array} \right.\end{array} \right.\]
⇔ \[\left[ \begin{array}{l}\left\{ \begin{array}{l}x < 1\\x > 5\end{array} \right.\\1 < x < 5\end{array} \right.\] (vô lí)
Vậy 1 < x < 5.