navalpike wrote:Ahhh, I can't believe I did that. Thanks for correcting me.
Ron, as my post stated above, do you know of a similar algebraic approach that we can apply to S2. As I mentioned, the first time around I got the question wrong and chose D because I failed to consider the right numbers for LCM 30.
Thanks,
unfortunately, no, i can't think of a simple algebraic approach for numbers with a given LCM.
(you could try to write the numbers as something like 30/m and 30/n, but whatever you do with those numbers is going to be obnoxiously difficult. worse yet, the 'm' and 'n' in these expressions are the EXACT SAME numbers that you'll get if you just let 'm' and 'n' represent the factors themselves.)
this is how a LOT of gmat divisibility problems work, by the way. in fact, i'd say that, among divisibility problems, there are probably more problems that DON'T have simple all-algebraic solutions than problems that do have such solutions.
Ron has been teaching various standardized tests for 20 years.
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