Chapter 8 - Section 8.2 - Multiplying and Dividing Radicals - Exercise Set - Page 585: 32

$x\sqrt{17}$

Getting the perfect factors and then extracting its root, the simplified form of the given expression, $ \sqrt{17x^2} ,$ is \begin{array}{l}\require{cancel} \sqrt{x^2\cdot17} \\\\= \sqrt{(x)^2\cdot17} \\\\= x\sqrt{17} .\end{array}