(p+q)(p+3r)
Step-by-step explanation:
p²+pq+3qr+3pr
Do the grouping p²+pq+3qr+3pr=(p²+pq)+(3qr+3pr), and factor out p in the first and 3r in the second group.
p(p+q)+3r(p+q)
Factor out common term p+q by using distributive property.
(p+q)(p+3r)