Abstract:
This article project discusses the multiplicative functions commutable with sums
of squares. In this article, suppose that k be an integer greater than or equal to
3. It is shown that if a multiplicative functions f satis es f(x2
1 + x2
2 + · · · + x2
k) =
f(x1)2 + f(x2)2 + · · · + f(xk)2 for all positive integers xi, then f is the identity
function.