Question

a4 + b4 + c4 + d4 = (a + b + c + d)4 where variables a, b, c and d can be any positive integer, negative integer or zero. what is the answer

Answer 1

There is no single answer. Any choice of integers
`(a,b,c,d)=(n,0,0,0)` satisfies the equations, since


`n^4+0^4+0^4+0^4=n^4`

`(n+0+0+0)^4=n^4`