Diophantine drives me crazy !

Determine the number of integral solutions ( x , y , z ) (x, y, z) with x , y , z |x|, |y|, |z| distinct, of x y z = 12. |x|·|y|·|z| = 12.

96 84 134 12

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1 solution

Factorizing gives 12=1·2·2·3, and thus, for |x|,|y| and |z| to be distinct, the possibilities for the three absolute values |x|, |y|, |z| are (ignoring order) (1, 2, 6) and (1, 3, 4). Each of these can be ordered in six different ways, and then, for each of the six ways, we can have 0, 1, 2, or 3 of the integers positive, making a total of eight ways. Thus altogether there are 2 · 6 · 8 = 96 solutions to identify.

What about (1,-1,12).

Ankit Kumar Jain - 6 years, 2 months ago

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Yes, a very important point ! I should add more solution sets :- ( 1 , 1 , 12 ) , ( 1 , 1 , 12 ) , ( 1 , 1 , 12 ) , ( 1 , 1 , 12 ) (1,-1,12), (-1,1,12), (1,-1,-12), (-1,1,-12) . Thanks a lot, but since I can't change the solution ( there is no such option), I prefer to edit the question as x , y |x|,|y| and z |z| distinct. I hope that works fine. Thanks !

Venkata Karthik Bandaru - 6 years, 2 months ago

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Welcome Karthik. But I must say the question was really good.

Ankit Kumar Jain - 6 years, 2 months ago

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@Ankit Kumar Jain Thanks a lot, I am glad that you felt so !

Venkata Karthik Bandaru - 6 years, 2 months ago

Great solution. Karthik I solved the problem.

Ritvik Vantipalli - 6 years, 2 months ago

A nice problem. I forgot abut the sign!

Niranjan Khanderia - 6 years, 2 months ago

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