[tex]x^2-ax+1,25=0\\
\Delta_x=a^2-4\cdot1\cdot1,25=a^2-5[/tex]
Pentru ca ecuatii sa aiba solutiile reale distince,
[tex]\Delta_x\ \textgreater \ 0 \Leftrightarrow a^2-5\ \textgreater \ 0 \Leftrightarrow a^2\ \textgreater \ 5\\
\Leftrightarrow a\ \textgreater \ \sqrt5 \ sau \ a\ \textless \ -\sqrt5\\
\Rightarrow a \in \mathbb{R}\smallsetminus[-\sqrt5,\sqrt5][/tex]
