Để C dương thì xảy ra các trường hợp:
\(\orbr{\begin{cases}\frac{1}{2}-x>0;\frac{1}{3}-x>0\\\frac{1}{2}-x< 0;\frac{1}{3}-x< 0\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}x< \frac{1}{3}\\x>\frac{1}{2}\end{cases}}\)
Để C > 0
=> \(\hept{\begin{cases}\frac{1}{2}-x< 0\\\frac{1}{3}-x< 0\end{cases}}\)hoặc \(\hept{\begin{cases}\frac{1}{2}-x>0\\\frac{1}{3}-x>0\end{cases}}\)
Nếu \(\hept{\begin{cases}\frac{1}{2}-x< 0\\\frac{1}{3}-x< 0\end{cases}\Rightarrow\hept{\begin{cases}x< \frac{1}{2}\\x< \frac{1}{3}\end{cases}\Rightarrow}x< \frac{1}{3}}\)
Nếu \(\hept{\begin{cases}\frac{1}{2}-x>0\\\frac{1}{3}-x>0\end{cases}\Rightarrow\hept{\begin{cases}x>\frac{1}{2}\\x>\frac{1}{3}\end{cases}\Rightarrow}x>\frac{1}{2}}\)
Vậy \(C>0\Leftrightarrow\orbr{\begin{cases}x< \frac{1}{3}\\x>\frac{1}{2}\end{cases}}\)