Thread: Strange Problem has me stumped

Here is the question:
a, b and c are 3 different, positive integers, and (ab)^2 = abc.

Which of the following is a possible value for c?
1
5
9
12

I know the answer is 12, but i do not understand how to get this, aside from guess and check.
Any help would be appreciated.

Hi,

since then .

Can you multiply 2 different positive a and b to get, say 9 where neither a or b are 9?
How about 1 and 5?