If n ∈ N, then x2n−1+y2n−1 is divisible by
x + y
x - y
x2 + y2
x2+xy
x2n−1+y2n−1 is always contain equal odd power.
So it is always divisible by x + y.
Prove that x2n−1+y2n−1 is divisible by x+y for all n∈N.