The rules are:
1. When the BASES are the same, to MULTIPLY, you ADD the EXPONENTS.
2. When the EXPONENTS are the same, to MULTIPLY, you MULTIPLY BASES.
So
is true and is just a case of rule 2.
What there are no GENERAL rules for are:
1.
, when V is a variable.
2.
, when a variable V is an exponent in one term and not in another.
Edwin