Talk:Field of definition

[September 2008 query]
The article says that if K is not algebraically closed than every set of equations is equivalent to a single equation. Is there any reference for this statement? how can it be proved? it is obviously equivalent to finding a polynomial in k variables with a single solution.

132.77.4.129 (talk) 13:07, 9 September 2008 (UTC) Doron S