| [ back to MATH 102/03 home ] | revised 2001-10-14 |
Copyright © 2001 Stan Brown
An earlier document told you how to graph functions wth the TI-83. Once you have a function graphed, you can show its inverse automatically.
For purposes of illustration, let's use this function:
f(x) = sqrt(x-5)
You know from your algebra work that the inverse is
f-1(x) = x²+5, x >= 0
Graph the original function f as y1, using
the techniques you already know.
To graph the inverse,
Press [2nd] [DRAW] -- look
for DRAW above the [PRGM] button in the
middle of the black keys.
You want DrawInv, which is menu
selection 8, so either press [8] or scroll down to that
selection and press [ENTER]. That pastes the comamnd
DrawInv to your home screen.
Now you have to tell the TI-83 which function you want the
inverse of, namely Y1. To paste Y1 to the
home screen, press [VARS] [>] [1] to bring up the y
list, then [1] to select Y1. Your home
screen should now have the command DrawInv Y1.
Press [ENTER] to execute the command. The graph
screen will appear and the Ti-83 will draw the inverse function.
Unfortunately, all you can do with the inverse is look at it. You can't trace or do other things.
But at least you can use it to check your work. For instance, you see that the inverse of our sample function appears only in the positive x region. The inverse you calculated algebraically, x²+5, has a domain in both the positive and negative reals, but from drawing the inverse on the TI-83 you can see that you need to restrict the inverse function's domain to match teh restricted range of the original function.