Question

find a pair of factors by using the difference of two squares

Answer 1

Let us say the number is 9

9 can be written as the difference of 2 squares by

5^2 - 4^2 = 9 [Let us keep that aside for a while]

There is an identity \[a^2 - b^2 = (a+b)(a-b) ~~ <-- These ~~ are ~~the~~2 ~~factors.\]
So
5^2 - 4^2 = 9 = (5+4)(5-4) = 9*1
So 2 factors of 9 are 9 and 1. :)

I am not sure if this is what the question was, but I HOPE YOU UNDERSTAND THE CONCEPT. :)