\(\textbf{Zadatak 3.}\) Odredi rješenja bikvadratne jednadžbe:

\begin{equation*}
x^{4}-10x^{2}+9=0
\end{equation*}

\(\textbf{Rješenje:}\)

\begin{equation*}
x^{4}-10x^{2}+9=0\\
x^{2}=w\\
w^{2}-10w+9=0\\
w_{1,2}=\frac{10\pm 8}{2}\end{equation*}

\begin{equation*}
w_{1}=1;\:\:w_{2}=9
\end{equation*}

\begin{equation*}
x_{1,2}=\pm \sqrt{w_{1}}\\ 
x_{1,2}=\pm \sqrt{1}\\
x_{1}=-1,\:\:x_{2}=1\\
\end{equation*}

\begin{equation*}
x_{3,4}=\pm \sqrt{w_{2}}\\
x_{3,4}=\pm \sqrt{9}\\
x_{3}=-3,x_{4}=3
\end{equation*}