## Precalculus (6th Edition)

$\Rightarrow 5p^{4}q$
$\left( p+q\right) ^{5}=p^{5}+\binom 5 1 p^{4}q+\ldots +\binom 5 4 pq^4+q5$ $\binom 5 1 =\dfrac {5!}{1!\left( 5-1\right) !}=5$ then second term will be $\Rightarrow 5p^{4}q$