4.3A   Piecewise Functions w/TI-84

Graphing Piecewise Functions using the TI-84 Plus Grapher

   We worked at graphing piecewise functions using Desmos, now we will look at graphing piecewise functions using a graphing calculator.

Method 1 - Graphing each function separately, with color.

      On the right is a piecewise function with 3 functions and their conditions.

     Again, we will graph these functions separately for color.

  Steps:

       Y1 = (x + 8)/(x < -1)         

              Notice the function is in the numerator, and the denominator is the condition.

              Both need to be in parentheses.

              To include the < symbol:  Press the following keys:    2nd Math:  TEST  5

      Y2 = x2/(( -1 ≤ x) and (x ≤ 2))     

             Again, the function is the numerator, and the denominator is the condition.

             Notice the parentheses in the denominator:  enclose each condition within parentheses.

             To include the ≤ symbol -   Press the following keys:     2nd Math:  TEST 6

             To include the and between each condition - Press the following keys:   2nd Math: LOGIC  1

    Y3 = (1 - x)/(x > 2)                

              Again, the function is the numerator, and the denominator is the condition.

              Both need to be in parentheses.

               To include the > symbol -  Press the following keys:   2nd Math:  TEST 3

Make sure your window is 

Xmin = -10     Xmax = 10      

Ymin = -10      Ymax = 10 

Zoom 6: ZStandard

Method 2 - Graphing the piecewise function as one function - no color.

Example 1

       A function is given at right, and the syntax used as the input for the grapher is given below.

  Steps for inputting the equation in a graphing calculator.

             Notice that the function and its condition are multiplied. 

             The second function and its condition are added to the first function and its condition.

             Type the first the equation times its condition (-2x + 5) (x ≤ 2)    

                       Press 2nd Math: TEST 6: ≤

             Include the + key then type the second equation times its condition (x + 1) (x > 2)           

                      Press 2nd Math: TEST 3: >

             Press the ZOOM: 6:ZStandard.

Example 2

    The piecewise function at the right has three conditions, of which one is a conjunction. 

     The syntax and process will be the same except for  -4 ≤ x < 0.

     This expression, -4 ≤ x < 0, will be typed as follows:    (-4 ≤ x)(x < 0).   

                 Notice that the conjunction's conditions are multiplied.