Question

http://prntscr.com/au0mwq

Answer 1

@jim_thompson5910

Answer 2

Of course, it is not a difference of squares, since it has three terms, so it is a trinomial.

Answer 3

A difference of squares has only two terms. One or both terms may be compounded of binomials... for example:
\[(x+3)^2-4\]
This expression may be classified as a difference of squares.
If we factor it, we get:
\[(x+3)^2-4=[(x+3)+4]\,[(x+3)-4]\]
Of course, you can add and subtract 3 and 4.