Faustus 12.04.2012 03:46 Prove that $x^3+y^3+z^3+t^3=1999$ has infinitely many soln. over $\mathbb{Z}$.
subham1729 12.04.2012 04:01 Put $x=10-b ,y=10+b ,z=-(d+1)/2 ,t=(d-1)/2 $ with $d$ is odd. and $d^2 -80b^2=1$ ,satisfy the given relation.
K.N 21.09.2016 09:55 subham1729 wrote: Put $x=10-b ,y=10+b ,z=-(d+1)/2 ,t=(d-1)/2 $ with $d$ is odd. and $d^2 -80b^2=1$ ,satisfy the given relation. Nice solution But what is the motivation?