ANSWER:
[tex](7n+12)\cdot(7n+12)[/tex]STEP-BY-STEP EXPLANATION:
We have the following polynomial:
[tex]49n^2+168n+144[/tex]We can see that this is the case of a perfect square trinomial, therefore:
[tex]\begin{gathered} (a+b)^2=a^2+2ab+b^2 \\ \text{ in this case:} \\ a=7n \\ b=12 \\ \text{ therefore:} \\ 49n^2+168n+144=(7n+12)^2 \\ (7n+12)^2=(7n+12)\cdot(7n+12) \end{gathered}[/tex]