(p+q) (p-q) ;(a+c) (c-a)

Question

(p+q) (p-q) ;(a+c) (c-a)

Answer 1

(p+q)(p-q)= p²-pq+pq-q²= p²-q²

(a+c)(c-a)= ac-a²+c²-ac= c²-a²