I want to show (6) on that page. I can show it using (7), but we aren't supposed to do that. I already proved (5), and my prof says to use the fact that (5) is true to get the answer.
The Attempt at a Solution
Here's what I tried:
δ(x2 - a2) = δ((x-a)(x+a))
I'm not sure how to use (5), because here a is not multiplying x. I'm not sure where to go from here.