Question

Write the function as a piecewise function.
f(x) = 3x + |x|

Answer 1

Conceptually, it would help you to graph it.

Answer 2

Rember |x|=x when x>=0 and -x when x<0, so you can write it like this:

\[ f(x) = \left \{ \begin{matrix} 4x & \mbox{if }x\geq0
\\ 2x & \mbox{if }x<0\end{matrix}\right. \]