The polynomial 9x2+3x3y2z is what degree?

In polynomials, when you are asked for its degree, you are to determine its highest degree of which the variable is raised to. For this example, one might argue that the highest degree is 3 at x³. But there is a rule that for polynomials containing implicit terms in the equation, you add up their exponents. Now, this is not applicable in algebraic operations. When you multiply the terms x³y²z, it does not become (xyz)⁶. This is not valid because they don't have common bases. The rule of adding up exponents is only applicable for classification. Therefore, the polynomial given is in the 6th degree.