The square of the difference of two numbers

Answer: The difference between consecutive square numbers is always odd. The difference is the sum of the two numbers that are squared ... The difference between alternate square numbers is always even; it is twice the sum of the two numbers that are squared.

Let's consider 2 numbers be 'a' and 'b'

Then

Square of difference of two numbers means square of difference of a-b which equals:

= (a-b) ^2

=a^2+2ab+b^2