Ta có

$\Delta ={{({{m}^{2}}+4)}^{2}}-4(3{{m}^{2}}+3)={{m}^{4}}-4{{m}^{2}}+4={{({{m}^{2}}-2)}^{2}}\Rightarrow \left[ \begin{align}  & {{3}^{x}}={{m}^{2}}+1 \\  & {{3}^{x}}=3 \\ \end{align} \right.$ $\Leftrightarrow \left[ \begin{align}  & x={{\log }_{3}}({{m}^{2}}+1) \\  & x=1 \\ \end{align} \right.$

Do đó ta có ${{x}_{1}}{{x}_{2}}={{\log }_{3}}({{m}^{2}}+1).1={{\log }_{3}}({{m}^{2}}+1)$