Question

Tìm x để :

\(\dfrac{x-5}{x-7}>0\)

Answer 1

\(\Leftrightarrow\left[{}\begin{matrix}\left\{{}\begin{matrix}x-5>0\\x-7>0\end{matrix}\right.\\\left\{{}\begin{matrix}x-5< 0\\x-7< 0\end{matrix}\right.\end{matrix}\right.\)\(\Leftrightarrow\left[{}\begin{matrix}\left\{{}\begin{matrix}x>5\\x>7\end{matrix}\right.\\\left\{{}\begin{matrix}x< 5\\x< 7\end{matrix}\right.\end{matrix}\right.\)\(\Leftrightarrow\left[{}\begin{matrix}x>7\\x< 5\end{matrix}\right.\)

Vậy...

Answer 2

\(bpt\Leftrightarrow\left[{}\begin{matrix}\left\{{}\begin{matrix}x-5>0\\x-7>0\end{matrix}\right.\\\left\{{}\begin{matrix}x-5< 0\\x-7< 0\end{matrix}\right.\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}\left\{{}\begin{matrix}x>5\\x>7\end{matrix}\right.\\\left\{{}\begin{matrix}x< 5\\x< 7\end{matrix}\right.\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x>7\\x< 5\end{matrix}\right.\)

Vậy .......

Answer 3

Ta có:\(\dfrac{x-5}{x-7}>0\)

  \(\Leftrightarrow\left[{}\begin{matrix}\left\{{}\begin{matrix}x-5>0\\x-7>0\end{matrix}\right.\\\left\{{}\begin{matrix}x-5< 0\\x-7< 0\end{matrix}\right.\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}\left\{{}\begin{matrix}x>5\\x>7\end{matrix}\right.\\\left\{{}\begin{matrix}x< 5\\x< 7\end{matrix}\right.\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x>7\\x< 7\end{matrix}\right.\)

Answer 4

Ta có: \(\dfrac{x-5}{x-7}>0\)

\(\Leftrightarrow\left[{}\begin{matrix}x-5< 0\\x-7>0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x< 5\\x>7\end{matrix}\right.\)