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More Graphing
on the TI-89 Titanium and the TI Voyage 200

From the Graph Screen

To get the GRAPH screen:
green diamond and F2 after entering expressions into Y=.

What is available from this graphing screen?


#6 Zoom Standard creates
a 10 x 10 pixel window.
F3 Trace, F4 Re-draw

F5 - Math


F6 -
Draw Commands

F7 - Pencil



Piecewise Defined Functions

To graph a piecewise function, you must specify boundaries and expressions for each piece.

Example:  Graph

Method 1:
Entering separate sections
When entering more than 2 entries, it will be necessary to utilize more than one  Y=  position.  The | command, which can be read “with”, is needed.
TI-89:  | is its own key
Voyage:  | is located above the K
Method 2:
Using WHEN (for two pieces).
To get when, type it in or use CATALOG.

when(condition, trueExpression, falseExpression)
Example:  Graph


The function is entered using the WHEN command.

DOT style is chosen to avoid having the sections of the graph connected.

Here is the graph in dot mode.
It is possible to enter more than two sections by "nesting" the when command.  Nesting means placing one function inside of another function.


Algebra and Composition of Functions

Remember to get the Y1 variables from the VAR menu.


Note the syntax for entering the functions.
Hint: Composition of functions:  It is possible that g(f (x)) may give an error if DEFINE is used.  If this problem occurs, try to define f and g using a variable other than x (such as a), and then use x for the composition.


Inverse Functions


             Graph the inverse of
                    f (x) = 2x + 3.

Enter f (x) into Y1.
From the Graph Screen, choose F6, #3 DrawInv (or use Catalog)
From the Home Screen, DrawInv

Remember that Y1 is obtained from 2nd VARS above the subtraction key.


Or check to see if your algebraic inverse answer is correct.
1. Enter f (x) into Y1.
2. Enter your algebraic inverse answer into Y2.
3. Turn off Y2
4. DrawInv Y1(x)
5. Turn on Y2 with bubble animation
6. Graph
If your answer is correct the bubble will follow the path of the drawn inverse.


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