Answer
$P(p-3 q)^2=P p^2-6 P p q+9 P q^2$
Work Step by Step
First expand $(p-3 q)^2$ and then multiply the result by $P$. Therefore
$$
\begin{aligned}
P(p-3 q)^2 & =P(p-3 q)(p-3 q) \\
& =P\left(p^2-3 p q-3 p q+9 q^2\right)\\
&=P\left(p^2-6 p q+9 q^2\right) \\
& =P p^2-6 P p q+9 P q^2
\end{aligned}
$$
