Power Function on Strictly Positive Base is Continuous/Real Power
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Theorem
Let $a \in \R_{>0}$.
Let $f : \R \to \R$ be the real function defined as:
- $\map f x = a^x$
where $a^x$ denotes $a$ to the power of $x$.
Then $f$ is continuous.
Proof
By definition, $a^x$ is the unique continuous extension of $a^r$, for rational $r$.
By definition, continuous extensions are continuous.
Hence the result.
$\blacksquare$
Also see
- Power Function to Rational Power permits Unique Continuous Extension, where such a unique continuous extension is shown to exist.