Finding the root or zero of a function.
Note that an x -intercept of the graph of a function f(x) is the same as a root of f(x).
TI-86 : Use ROOT.
Path: Graph, More, Math, Root
How to use: Press ROOT, then the calculator asks for the left bound. Use the directional keys to move the cursor to a point slightly to the left of the desired root, then press
ENTER. Repeat for the right bound. Note that the calculator displays arrows near the top of the screen, showing the left and right bounds you selected. Finally, the calculator asks for a guess. Move the cursor to a point between the left and right bounds and press
ENTER. Make sure you see the word ZERO on the screen--if not, the procedure has not been completed.
TI-83 : Use ZERO.
Path: 2nd Calc, Zero
How to use: Press ZERO, then the calculator asks for the left bound. Use the directional keys to move the cursor to a point slightly to the left of the desired root, then press
ENTER. Repeat for the right bound. Note that the calculator displays arrows near the top of the screen, showing the left and right bounds you selected. Finally, the calculator asks for a guess. Move the cursor to a point between the left and right bounds and press
ENTER. Make sure you see the word ZERO on the screen--if not, the procedure has not been completed.
TI-82 : Use ROOT.
Path: 2nd Calc, Root
How to use: Press ROOT, then the calculator asks for the lower bound. Use the directional keys to move the cursor to a point slightly to the left of the desired root, then press ENTER. You move to the left because you are choosing an xvalue and lower values of x occur to the left. Repeat for the upper bound. (Note that higher values of x occur to the right.) Also note that the calculator displays arrows near the top of the screen, showing the lower and upper bounds you selected. (To remove these arrows from the display, press Zoom-Standard.) Finally, the calculator asks for a guess. Move the cursor to a point between the left and right bounds and press ENTER. Make sure you see the word ROOT on the screen--if not, the procedure has not been completed.
TI-85 : Use ROOT.
Path : Graph, Math, Root
How to use: Press ROOT, then cursor to desired root (use the directional keys), then press ENTER. Make sure you see the work ROOT on the screen--if not, the procedure has not been completed.
All Models:
For an x -intercept, of course the y -coordinate is 0. You may notice that the y - coordinate looks like -4E-7. Since this represents -4 x 10
-7
, it is virtually zero. When you see a number like this, with the negative after the E, just replace it with zero. Some small machine error occurred which can be ignored.