Question

tìm x 

x-3/x-4 >0

Answer 1

Đặt \(f_{\left(x\right)}=\dfrac{x-3}{x-4}\)

- Lập bảng xét dấu :

- Từ bảng xét dấu : -Để f(x) > 0 \(\Leftrightarrow\left[{}\begin{matrix}x>4\\x< 3\end{matrix}\right.\)

Vậy ...

Answer 2

\(\dfrac{x-3}{x-4}>0\)

\(\Rightarrow\left[{}\begin{matrix}\left\{{}\begin{matrix}x-3>0\\x-4>0\end{matrix}\right.\\\left\{{}\begin{matrix}x-3< 0\\x-4< 0\end{matrix}\right.\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}\left\{{}\begin{matrix}x>3\\x>4\end{matrix}\right.\\\left\{{}\begin{matrix}x< 3\\x< 4\end{matrix}\right.\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x>4\\x< 3\end{matrix}\right.\)