Answer
$=pq \cdot pq \cdot pq \cdot pq = (p \cdot p \cdot p \cdot p)(q \cdot q \cdot q \cdot q) = p^4q^4$
Work Step by Step
$a^m \cdot a^n = a^{m+n}$
Use the rule above to obtain:
$(pq)^4=pq \cdot pq \cdot pq \cdot pq = (p \cdot p \cdot p \cdot p)(q \cdot q \cdot q \cdot q) = p^4q^4$
