Given the graph of a function,
we can sketch the graph of
by considering the effect of taking the modulus of
on positive and negative values of
For
so the part of the graph for which
is unchanged.
For
This means that
so that the point to be plotted is
which is just the point
reflected in the
– axis. The effect of taking the modulus of each value ofis then to erase the part of the graph left of the- axis and replace it by the reflection in the- axis of the part of the graph to the right of the y axis.
Example: To plot
draw the part of the graph forand reflect this part of the graph in the- axis to obtain the part of the graph for
The union of these two parts is
