To Evaluate Functions using the TI-83 series

Example: Given find f(-3), f(5), f(8)

Method 1: Using the VARS menu

1. Enter your formula in Y1

2. Press 2nd Mode (that’s the QUIT sequence that will take you back to your HOME screen.

3. On the keyboard, find the VARS key (just to the left of the CLEAR keyon the right side)

Press the following key sequence: VARS  Y-Vars then ENTER when FUNCTION is highlighted. That will pull up the function list Y1 through Y0

4. Since you’re formula is stored in Y1, Press ENTER while 1: is highlighted

That will put Y1 on your home screen to use. Then in parentheses put the value you want it to calculate and press ENTER

5. Then Press 2nd ENTER to pull the entry back onto the home screen, use the back arrow to change the value and press ENTER again

You will be able to see both the input on the left and the output on the right side of the screen for a number of entries.

Method 2: Using the Graph

Enter your formula in Y1

  • Make sure you choose a reasonable window and can see the graph
  • Press 2nd TRACE (that will get you to the CALC function window)
  • Press #1 (VALUE)
  • Enter the X-value you want it to find
  • It will jump to that point on the graph and return both the X and Y values at the bottom of the screen, and show you the point on the graph if it’s in the window

You can repeat the process and find the other values as well (although it won’t show you the point if it’s vertically off the screen)

USER WARNING: This method can be dangerous. If the window you’re using does not contain the x-value you’re looking for the calculator will not show the y-value

it says invalid because you didn’t give it a proper X-window to find the value (remember the window is similar to giving it an explicit domain )

Method 3: Using the TABLE

Enter your formula in Y1 then press 2nd Window (that will bring you to the place where you can set the format for the table)

  • Make TblStart = your first value and let Tbl = 1
  • Leave the rest AUTO and AUTO
  • Press 2nd GRAPH (takes you to the table) and just scroll through the values using the up and down cursor arrow

There is also a downside to this method. If you were also asked for f(2.35) you could not easily enter it without changing the Table Setup.

There are three different methods for evaluating any kind of function you can enter into the TI-83. Practice with them and use them to make your work easier.

Work Smarter…..not Harder……

Evaluating on the TI-83/84 series page 1Fitzpatrick