Question

(2x - 7). (x+3)<0

Answer 1

Vì \(\left(2x-7\right)\left(x+3\right)< 0\)

\(\Rightarrow2x-7>0;x+3< 0\)

hoặc \(2x-7< 0;x+3>0\)

+) \(\left[{}\begin{matrix}2x-7>0\Rightarrow2x>7\\x+3< 0\Rightarrow x< 0-3\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x>\dfrac{7}{2}\\x< -3\end{matrix}\right.\) \(\Rightarrow-3>x>\dfrac{7}{2}\left(loại\right)\)

+) \(\left[{}\begin{matrix}2x-7< 0\Rightarrow2x< 7\\x+3>0\Rightarrow x>0-3\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x< \dfrac{7}{2}\\x>-3\end{matrix}\right.\) \(\Rightarrow-3< x< \dfrac{7}{2}\) (t/m)

Vậy \(-3< x< \dfrac{7}{2}.\)

Answer 2

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