Answer
If we muliply out (distribute) the expression
$(a+b)(a-b) $ using FOIL, we obtain
$=a^{2}-ab+ba-b^{2}$
$=a^{2}-b^{2}$, because the middle two terms cancel.
So, when we see any expression of the form $A^{2}-B^{2}$,
(a difference of squares of A and B),
we factor it with $(A+B)(A-B)$
Work Step by Step
Given above.
