\[\boxed{\mathbf{216.}}\]
\[\textbf{а)}\ P = p \cdot q;\]
\[\textbf{б)}\ P = q^{4};\]
\[\textbf{в)}\ P = 1 - q^{6};\]
\[\textbf{г)}\ P = pq^{2} + pq^{3} + pq^{4} =\]
\[= p\left( q^{2} + q^{3} + q^{4} \right) =\]
\[= p \cdot \frac{q^{2}\left( 1 - q^{3} \right)}{1 - q} = q^{2}\left( 1 - q^{3} \right).\]