Question

Tìm x khi:

a) x -7 phần 2 < 0

b) x + 3 phần x + 5 < 0

Answer 1

a/ \(\dfrac{x-7}{2}< 0\Rightarrow x-7< 0\Rightarrow x< 7\)

Vậy........

b/ \(\dfrac{x+3}{x+5}< 0\)

\(\Rightarrow\left[{}\begin{matrix}\left\{{}\begin{matrix}x+3< 0\\x+5>0\end{matrix}\right.\\\left\{{}\begin{matrix}x+3>0\\x+5< 0\end{matrix}\right.\end{matrix}\right.\)\(\Rightarrow\left[{}\begin{matrix}\left\{{}\begin{matrix}x< -3\\x>-5\end{matrix}\right.\\\left\{{}\begin{matrix}x>-3\\x< -5\end{matrix}\right.\end{matrix}\right.\)

\(\Rightarrow-5< x< -3\)

Vậy........