Mathematical puzzle

India
January 1, 2008 2:21pm CST
Give me integers x,y,z such that x^3 + y^3 = z^3. Do think well before you answer! The solution may be trickier than it seems at a casual glance! All the best!
1 person likes this
4 responses
@opinione (749)
• Italy
2 Jan 08
If I'm not wrong in what I've read, since I'm not a matematician, I can tell you that Fermat first supposed (and perhaps demonstrated, but just to himself...) that there was such a theorem on integers (the so called third Fermat's t.) that you can't have solutions of the diophantine equation: x^n+y^n=z^n for n2. Of course n=2 has as solutions the so called pitagorean triplets or thriads. Euler demonstrated the t. for n=3 and for other cases. In 1995 (I'm not sure of the date and of the name of the scientist) a certain English professor Vailey, who had spent nearly all his life in attempting to solve the problem reached finally a solution universally accepted. Later on, many other Authors have given many different demonstrations... on the acceptability of which nothing I can tell you. But, what about 3^3+4^3+5^3=6^3 and, what could be its geometrical interpretation (apart from the fact that U can build a complete cube using the brics deriving from other three different cubes... I wanna know if exists such a figure where you can apply this result, since for n=2 there are special rectangle triangula). best regards
1 person likes this
• India
4 Jan 08
well you are right. as for the equation x^3 + y^3 + z^3 = w^3, it has non zero integral solutions! and as for the geometric interpretation of fermat's last theorem, it says that all elliptic functions are modular (if you know what they mean geomectrically!)
@opinione (749)
• Italy
5 Jan 08
Thanks for the kind reply! I'm wondering wether exists such a sort of 'generalization' of Pitagora's t. : y^n = sum[k=1:n] (x_k)^n In other words, n is the minimum number of integers elevated to a certain power n whose summation gives another integer elevated to the same power n. 1) is it possible? 2) has it already been demonstrated? 3) under what conditions?
@cyberfluf (4996)
• Netherlands
1 Jan 08
^3 means 3 times z, as in z x z x z = ? I need to know before I can think of a possibe solution.
• Turkey
1 Jan 08
yeah, ^ always means "over", because we cannot write a number actually over another number here.
@cyberfluf (4996)
• Netherlands
2 Jan 08
Thank you, this way I'll at least know what the meaning of the puzzle is :) Unsure if I'll be able to solve it, but this sure will help me while I'm trying.
1 person likes this
• Philippines
2 Feb 08
1 2 3
• Turkey
1 Jan 08
I think you want 3 different integers, otherwise it will be x=y=z=0 easily. So, after many minutes of desperate thinking and calculating, at one moment, I realized that integers can also be negative! So the answer would be x=-1, y=1 and z=0. Am I right?
• India
2 Jan 08
Well you have one solution thats right... in fact, not just -1,1,0 but (n,-n,0) is a solution for any integer n. But are there any OTHER solutions as well? What if x,y,z are non zero? What if x,y,z are now positive natural numbers instead of integers?
1 person likes this
@uath13 (8192)
• United States
2 Jan 08
That being the case so long as y = -x then z would always be equal to 0, You could then use any number for x
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• Turkey
2 Jan 08
Hehe, I thought about that before realizing that integers can also be negative. I only found 6^3 + 8^3 = 9^3 - 1. There should be a solution. If no one finds it, i'll write a code to try all posibilities. I'm a little obsessive.:)