The laws governing the combination of Exponents (Powers) are

(1)

(2)

(3)

(4)

(5)

(6)

(7)

where quantities in the Denominator are taken to be nonzero. Special cases include

(8)

and

(9)

for . The definition is sometimes used to simplify formulas, but it should be kept in mind
that this equality is a definition and not a fundamental mathematical truth.