Question

: Tim x biết (x + 3)(2x - 4) < 0

 

Answer 1

\(\left(x+3\right)\left(2x-4\right)< 0\)

\(\Rightarrow2\left(x+3\right)\left(x-2\right)< 0\)

\(\Rightarrow\left[{}\begin{matrix}\left[{}\begin{matrix}x+3>0\\x-2< 0\end{matrix}\right.\\\left[{}\begin{matrix}x+3< 0\\x-2>0\end{matrix}\right.\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}\left[{}\begin{matrix}x>-3\\x< 2\end{matrix}\right.\\\left[{}\begin{matrix}x< -3\\x>2\end{matrix}\right.\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x>-3\\x< 2\end{matrix}\right.\)

\(\Rightarrow-3< x< 2\)