Factor $LaTeX: \displaystyle 5 x^{3} + 45 x^{2} + 4 x + 36$ .

Grouping the first two terms and factoring out their GCF, $LaTeX: \displaystyle 5 x^{2}$ , gives $LaTeX: \displaystyle 5 x^{2}(x + 9)$ . Grouping the last two terms and factoring out their GCF, $LaTeX: \displaystyle 4$ , gives $LaTeX: \displaystyle 4(x + 9)$ . The polynomial now has a common binomial factor of $LaTeX: \displaystyle x + 9$ . This gives $LaTeX: \displaystyle 5 x^{2} \left(x + 9\right) +4 \cdot \left(x + 9\right) = \left(x + 9\right) \left(5 x^{2} + 4\right)$ .