Question 290118
(p+q)^2-2(p+q)-15
Think of (p+q) as x
x^2-2x-15
(x-5)(x+3)
(p+q-5)(p+q+3)

(p+q)^2-2(p+q)-15
You could work it out to
p^2+2pq-2p+q^2-2q-15
But either way you get
(p+q-5)(p+q+3)