Intermediate Algebra (6th Edition)

The given expression, $\sqrt[]{30} ,$ is closest to $5$ since $5^2=25.$ The given expression, $\sqrt[]{10} ,$ is closest to $3$ since $3^2=9.$ The given expression, $\sqrt[]{90} ,$ is closest to $10$ since $10^2=100.$ Hence, the perimeter of the given triangle, $\sqrt{30}+\sqrt{10}+\sqrt{90} ,$ is closest to \begin{array}{l}\require{cancel} 5+3+10 \\\\= 18 .\end{array} Hence, $\text{ Choice B .}$