Rules of exponents

Rule Notes
Definition \(x^n=\overset{n\text{-times}}{\overbrace{x\cdot x\cdot x\cdots x}}\) \(n\in\mathbb{N}\)
Comparison \(x^m=x^n\iff m=n\) \(x\neq 0,\pm 1\); i.e., no special bases
Same base
Different exponents*
\(x^m\cdot x^n=x^{m+n}\) Multiplication: add exponents
\(x^m\div x^n=x^{m-n}\) Division: subtract exponents
Same exponent
Different bases*
\(x^m\cdot y^m=(x\cdot y)^m\)
\(x^m\div y^m=(x\div y)^m\)
Double exponent* \((x^m)^n=x^{mn}\) Exponents are multiplied
Special exponents \(x^1=x\) An absent exponent means an exponent of \(1\)
\(x^0=1\) \(x\neq 0\)
Special bases \(0^n=0\) \(n\gt 0\)
\(1^n=1\)
\((-1)^n=\begin{cases} \phantom{-}1;& n\text{ is even} \\ -1;& n\text{ is odd}\end{cases}\)

* Rules for special bases and exponents are to be observed.

\(0^0\) is undefined because it implies dividing by zero.