College Algebra (11th Edition)

$x=\left\{ -4,4 \right\}$
Taking the square root of both sides, the solutions to the given equation, $x^2=16 ,$ are \begin{array}{l}\require{cancel} x=\pm\sqrt{16} \\\\ x=\pm\sqrt{(4)^2} \\\\ x=\pm4 .\end{array} Hence, the solution is $x=\left\{ -4,4 \right\} .$