Power Function on Base Greater than One is Strictly Increasing/Positive Integer

Theorem
Let $a \in \R$ be a real number such that $a > 1$.

Let $f: \N \to \R$ be the real-valued function defined as:
 * $f \left({ n }\right) = a^n$

where $a^n$ denotes $a$ to the power of $n$.

Then $f$ is strictly increasing.

Proof
Fix $n \in \N$.

Let $a > 1$.

From Ordering of Reciprocals:
 * $0 < \dfrac 1 a < 1$

From Power Function on Base between Zero and One is Strictly Decreasing: Natural Number:
 * $\left({\dfrac 1 a}\right)^{n+1} < \left({ \dfrac 1 a}\right)^n$

From Real Number to Negative Power: Positive Integer:
 * $\dfrac 1 {a^{n+1}} < \dfrac 1 {a^n}$

From Ordering of Reciprocals:
 * $a^n < a^{n+1}$

Hence the result.