The quadratic equation is given to be:
[tex]3x^2=36[/tex]
Divide both sides by 3:
[tex]\begin{gathered} x^2=\frac{36}{3} \\ x^2=12 \end{gathered}[/tex]
Recall the rule:
[tex]\mathrm{For\:}x^2=f\left(a\right)\mathrm{\:the\:solutions\:are\:}x=\sqrt{f\left(a\right)},\:\:-\sqrt{f\left(a\right)}[/tex]
Therefore, we have that:
[tex]x=\pm\sqrt{12}[/tex]
Simplifying the radical, we have:
[tex]\sqrt{12}=\sqrt{4\cdot3}=2\sqrt{3}[/tex]
Therefore, the solution is:
[tex]x=2\sqrt{3}\text{ or }-2\sqrt{3}[/tex]
