Ceiling of Root of Ceiling equals Ceiling of Root/Proof 1

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Theorem

$\ds \ceiling {\sqrt {\ceiling x} } = \ceiling {\sqrt x}$


Proof

\(\ds n\) \(=\) \(\, \ds \ceiling {\sqrt x} \, \) \(\ds \)
\(\ds \leadstoandfrom \ \ \) \(\ds n - 1\) \(<\) \(\, \ds \sqrt x \, \) \(\, \ds \le \, \) \(\ds n\) Integer equals Ceiling iff Number between Integer and One Less
\(\ds \leadstoandfrom \ \ \) \(\ds \paren {n - 1}^2\) \(<\) \(\, \ds x \, \) \(\, \ds \le \, \) \(\ds n^2\) Order is Preserved on Positive Reals by Squaring
\(\ds \leadstoandfrom \ \ \) \(\ds \paren {n - 1}^2\) \(<\) \(\, \ds \ceiling x \, \) \(\, \ds \le \, \) \(\ds n^2\) Number not greater than Integer iff Ceiling not greater than Integer
\(\ds \leadstoandfrom \ \ \) \(\ds n - 1\) \(<\) \(\, \ds \sqrt {\ceiling x} \, \) \(\, \ds \le \, \) \(\ds n\) Order is Preserved on Positive Reals by Squaring
\(\ds \leadstoandfrom \ \ \) \(\ds n\) \(=\) \(\, \ds \ceiling {\sqrt {\ceiling x} } \, \) \(\ds \) Integer equals Ceiling iff Number between Integer and One Less

$\blacksquare$