Proof & Step-by-step explanation:
We know that log ab = log a + log b and log a/b = log a - log b, so we substitute that in and get (log ab)(log a/b) = (log a + log b)(log a - log b) = (log a)^2 - (log b)^2.
I hope this helps! If you have any questions, feel free to ask! :)