III. Working With A Graph

B. MATH

1. ROOT

Use root to find the x-value where a function's graph crosses the x-axis. This is an extremely useful tool in solving equations.

Example 1: Find a root of the function shown in the first window. When you enter the left and right bounds, try to enter values that are relatively close to the zero so that other variations in the graph do not impede the process. After you enter a left bound and a right bound, the cursors shown should have the root between them. To enter the bounds you can enter the number directly or you can trace to a value. Press after the value is entered.

Enter.
Set a window.
Graph.
Access ROOT:

Enter a Left
Bound of x=-2.
Enter a Right
Bound of x=-1.5.
Ignore "Guess?"
and press enter.
This is the root.

Example 2: Use the ROOT function to solve the equation . You will graph the function and then find any roots shown. You might try a preset window first and then you can refine the window if needed.

Enter.
Use ZDECM
and graph.
Find the first
root as above.
Find the
second root.

 

1. ROOT
2. dy/dx
3. Integral
4. FMIN
5. FMAX
6. INFLC
7. YICPT
8. ISECT
9. DIST
10. ARC
11. TANLN

 

A. y(x)
B. MATH
C. FORMAT
D. EVAL
E. TABLE
F. TRACE
G. ZOOM