Question 8: Find x knowing: \(\left( {{x^2} – 4} \right).\left( {3{x^2} – 9} \right) = 0\)

We have:

\(\begin{array}{l} \left( {{x^2} – 4} \right).\left( {3{x^2} – 9} \right) = 0\\ \Rightarrow \left[\begin{array}{l}{x^2}-4=0\\{x^2}-3=0\end{array}\right\Rightarrow\left[\begin{array}{l}{x^2}=4\\{x^2}=3\end{array}\right\Rightarrow\left[\begin{array}{l}x=\pm2\\x=\pm\sqrt3\end{array}\right\end{array}\)

So the x values ​​are: \(\pm 2; \pm \sqrt 3 \)