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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.

 

 

 

 



                             
 



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