ANSWER:
[tex]\begin{gathered} (x+7i)\cdot(x-7i) \\ x=7i,-7i \end{gathered}[/tex]STEP-BY-STEP EXPLANATION:
We have the following expression
[tex]f(x)=x^2+49[/tex]we factor and we have:
[tex]\begin{gathered} x^2+49=0 \\ x^2=-49 \\ x=\sqrt[]{-49} \\ x=\pm7i \\ x=7i,-7i \end{gathered}[/tex]