Answer
$\color{blue}{(m+5+n^2)(m+5-n^2)}$
Work Step by Step
Group the first three terms together to obtain:
$=(m^2+10m+25)-n^4$
The trinomial is a perfect square trinomial in the form $a^2+2ab+b^2$ with $a=m$ and $b=5$.
RECALL:
$a^2+2ab+b^2=(a+b)^2$
Use the formula above to obtain:
$=(m+5)^2-n^4
\\=(m+5)^2-(n^2)^2$
The polynomial above is a difference of two squares.
Factor using the formula $a^2-b^2=(a+b)(a-b)$ with $a=m+5$ and $b=n^2$ to obtain:
$=[(m+5)+n^2][(m+5)-n^2]
\\=\color{blue}{(m+5+n^2)(m+5-n^2)}$
