I do know the standard procedure—square both sides, isolate square root, square again, check solutions to make sure they are real, etc. However, for a problem such as the above, how does one go about doing it?
I also know that there wouldn't be much of a problem by doing what I said; however, I'm fairly certain there's a more efficient, or at least less tedious, way of solving it.
The only clue I see is the $a^2-4a$ and $3a^2-12a$, where one would multiply to former by $3$ to get the latter, but nothing is clicking for me. If there is indeed a better way than squaring both sides, could someone point me to the right direction?