# How do you multiply (3y^3+9y+27)(-3y^2)?

Multiply each term in the parenthesis on the left by $\textcolor{red}{- 3 {y}^{2}}$:
$\left(\textcolor{red}{- 3 {y}^{2}} \times 3 {y}^{3}\right) + \left(\textcolor{red}{- 3 {y}^{2}} \times 9 y\right) + \left(\textcolor{red}{- 3 {y}^{2}} \times 27\right) =$
$- 9 {y}^{5} - 27 {y}^{3} - 81 {y}^{2}$