## Elementary and Intermediate Algebra: Concepts & Applications (6th Edition)

$9x^2$
$\bf{\text{Solution Outline:}}$ Use the definition of exponents to simplify the given expression, $(-3x)^2 .$ $\bf{\text{Solution Details:}}$ With an exponent of $2$, mutliply the given expression to itself. Hence, \begin{array}{l}\require{cancel} (-3x)^2 \\\\= (-3x)(-3x) \\\\= 9x^2 .\end{array}