# Chapter 5 - Number Theory and the Real Number System - 5.4 The Irrational Numbers - Exercise Set 5.4: 64

$\dfrac{13\sqrt{10}}{20}$

#### Work Step by Step

Rationalize the denominator by multiplying $\sqrt{10}$ to both the numerator and denominator: $=\dfrac{13\sqrt{10}}{\sqrt{40}(\sqrt{10})} \\=\dfrac{13\sqrt{10}}{\sqrt{400}} \\=\dfrac{13\sqrt{10}}{20}$

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