For a useful graph of a function you need to be able to see all characteristics (within the 'given' domain). These are:

• the points of intersection with the axes, i.e. the roots and the y-intercept;

• the asymptotes;

• the vertices, i.e. points where (local) maximum and minimum values occur, which you can find by using the trace option on your graphic calculator.

When all characteristics are visible, your graphic calculator can find them for you. It has a menu which enables you to have them calculated for you.