retain f(x) graph to the right of y-axis, truncate/ignore f(x)
graph to the left of y-axis, then reflect along y-axis.
this one can think and plot out with a grapher one. 
logic:
f(|x|) is defined by:
f(x) for x >= 0
f(-x) for x < 0
when x = -1, f(|-1|) = f(1)
when x = 1, f(|1|) = f(1)
==> reflect along y-axis
