N less than M to the N
From ProofWiki
Theorem
- $\forall m, n \in \Z_+: m > 1 \implies n < m^n$
Proof
| \(\displaystyle \) | \(\displaystyle n\) | \(=\) | \(\displaystyle 1 + 1 + \cdots \left({n}\right) \cdots + 1\) | \(\displaystyle \) | |||
| \(\displaystyle \) | \(\displaystyle \) | \(<\) | \(\displaystyle 1 + m + m^2 + \cdots + m^{n + 1}\) | \(\displaystyle \) | (as $m > 1$) | ||
| \(\displaystyle \) | \(\displaystyle \) | \(=\) | \(\displaystyle \frac {m^n - 1} {m - 1}\) | \(\displaystyle \) | Sum of Geometric Progression | ||
| \(\displaystyle \) | \(\displaystyle \) | \(\le\) | \(\displaystyle m^n - 1\) | \(\displaystyle \) | (as $m-1 \ge 1$) | ||
| \(\displaystyle \) | \(\displaystyle \) | \(<\) | \(\displaystyle m^n\) | \(\displaystyle \) |
$\blacksquare$
Source
- George E. Andrews: Number Theory (1971): $\S 1.1$: Corollary $1.1$