A student from Algebra II (4) has asked me this question using the Feedback. Notes on Functions from our Moodle page is a place to start. In terms of the test tomorrow, graphing piece-wise functions is the reference to "functions. "Take a look at the notes linked above. It will be important to know that f(x)=x-1 is the same as y=x-1. Ask me in class for more information...