## Elementary Algebra

$\approx -1.4$
Using the properties of radicals, a rational approximation (to the nearest tenth) of the given expression, $14\sqrt{2}-15\sqrt{2} ,$ is \begin{array}{l}\require{cancel} (14-15)\sqrt{2} \\\\= -1\sqrt{2} \\\\ \approx -1.4 .\end{array}