The modulus sign, as mentioned in our section on algebra, means the numerical value of the function is taken. For example, |2| = 2, and |-2| = 2. In graphing, to take the modulus of a function is to:

1. The parts of the graph above the x-axis does not change.

2. The parts of the graph below to x-axis is reflected to above it.

Graph of y = |x|.

                                      

Sketch the graph of y = |x² - 4x - 5|.

Solution:

Graph of y = x² - 4x - 5.

                                     

Graph of y = |x² - 4x - 5|