(x-2)*(x+5)>0 tìm tập hơp x biet

Đáp án:

\(S = ( – \infty ; – 5) \cup (2; + \infty )\)

Giải thích các bước giải:

\(\begin{array}{l}\left( {x – 2} \right)\left( {x + 5} \right) > 0\\ \Leftrightarrow \left[ \begin{array}{l}\left\{ \begin{array}{l}x – 2 > 0\\x + 5 > 0\end{array} \right.\\\left\{ \begin{array}{l}x – 2 < 0\\x + 5 < 0\end{array} \right.\end{array} \right. \Leftrightarrow \left[ \begin{array}{l}\left\{ \begin{array}{l}x > 2\\x > – 5\end{array} \right.\\\left\{ \begin{array}{l}x < 2\\x < - 5\end{array} \right.\end{array} \right. \Leftrightarrow \left[ \begin{array}{l}x > 2\\x < - 5\end{array} \right.\end{array}\) Vậy \(S = ( - \infty ; - 5) \cup (2; + \infty )\)