Answer
$(-\infty,-3)\cup(3,\infty)$
Work Step by Step
The solutions of $|u|\gt c $ are the numbers that satisfy $ u\lt -c $ or $ u\gt c.$
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$|x| \gt 3\Rightarrow\left\{\begin{array}{lll}
x\lt -3 & \Rightarrow & x\in(-\infty,-3) \\
or & & or\\
x \gt 3 & \Rightarrow & x\in(3,\infty)
\end{array}\right.$
Solution set: $(-\infty,-3)\cup(3,\infty)$
