Answer
$(x+5)(3x+11)$
Work Step by Step
First, since the polynomial $x^2 + 10x + 25$ is a perfect squrae, we can factor is using the formula $a^2+2ab+b^2=(a+b)^2$ where $a=x$ and $b=5$ to obtain:
$$
3(x^2 + 10x + 25) - 4(x + 5)=3(x+5)^2 - 4(x + 5)
.$$
Then, factoring $x+5$ out gives
$$
3(x+5)^2 - 4(x + 5)= (x+5)[3(x+5)-4]$$
DIstribute $3$ then combine like terms to obtain:
\begin{align*}
(x+5)[3(x+5)]-4&=(x+5)(3x+15-4)\\
&=(x+5)(3x+11)
\end{align*}
