Evaluating Algebraic Expressions,
Relations and Functions

When working with algebraic expressions, relations and functions, the graphing calculator can be used in a variety of ways to help evaluate the expression or determine the y-values for given domain elements.   The following methods may be used with expressions, relations and/or functions.  Relations and functions must be entered in the form of "y = ".

Consider the following methods for evaluating:

 Substitute Directly:
 Evaluate:        when   x = 5 On the Home Screen, type the expression replacing x with the desired value of 5. Place your desired value in parentheses to avoid any possible computational errors. Press ENTER. Your answer of 2 will appear on the Home Screen.
 Store Domain Values:
 Evaluate:        when   x = 5 On the Home Screen, store the value of  5  into the variable x using the STO► button.   Type 5  STO► x   and press ENTER.    Type the expression  on the Home Screen and press ENTER. Your answer of 2 will appear on the Home Screen.

 Store Domain Values and Utilize Y= :
 Evaluate:     y =    when   x = 5 Enter the function into Y= . On the Home Screen, store the value of  5  into the variable x using the STO► button.  Type 5  STO► x   and press ENTER.    Type Y1 on the Home Screen.  (VARS, arrow right to Y-VARS, #1 Function, Y1).  Press ENTER. Your answer will appear on the Home Screen.
 Use TRACE with Appropriate Window:
 Evaluate:     y =    when   x = 5 Enter the function into Y= . Set the WINDOW such that the desired value of 5 will appear on the x-axis.  (Zoom #6 will set a 10x10 viewing window.) Press GRAPH. Press TRACE. Now, just type the desired value on the keypad and hit ENTER. Your answer will appear at the bottom of the screen after y = , and the spider will mark the location on the graph.
 Use the TABLE:
 Evaluate:     y =    when   x = 5 Enter the function into Y= . Set the TBLSET (above WINDOW) such that the Indpnt:  ASK is highlighted.  The ∆Tbl can be set to any increment of your choosing and the starting value is of no importance.  Press TABLE (above GRAPH).  The table will appear empty and the X = entry will appear at the bottom of the screen.  Enter your value of x = 5 and the answer will appear in the table.  If you need another value entered, simply type it in at the bottom of the screen. Your answer(s) will appear as a listing in the table. OR Enter the function into Y= . Set the TBLSET (above WINDOW) such that the TblStart is set equal to your desired value of 5.  The ∆Tbl can be set to any increment of your choosing.  Choose AUTO, AUTO. Press TABLE (above GRAPH). Your answer will appear at the top of the table as the first value under the Y1 column.