Boundedness of Nth Powers

From ProofWiki
Jump to: navigation, search

Theorem

Power of Real Number greater than One is Unbounded Above

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

Let set $S = \left\{{x^n: n \in \N}\right\}$.


Then $S$ is unbounded above.


Power of Real Number between Zero and One is Bounded

Let $x \in \R$ be a real number.

Let $0 < x < 1$.

Let set $S = \left\{{x^n: n \in \N}\right\}$.


Then:

$\inf S = 0$

and:

$\sup S = 1$

where $\inf S$ and $\sup S$ are the infimum and supremum of $S$ respectively.