Remember that the function $f(x)=|x|$ is defined as:

${\displaystyle \begin{array}{cc}\multicolumn{1}{c}{y}& =x\hspace{0.5em}\mathrm{for}\hspace{0.5em}x\ge 0\\ \multicolumn{1}{c}{}& =-x\hspace{0.5em}\mathrm{for}\hspace{0.5em}x<0.\end{array}}$

Split up the domain of the function.