Find all integers $x$, $y$ and $z$ so that $x^2 + y^2 + z^2 = 2xyz$.
I'm thinking to start with all congruences like this
2^(2) kon 3 its = 1 ,
3^(2) kon 3 = 0.
Trying to test all kind of numbers with power $2$?
It's that right to solve it?
After that i get stuck some clue??