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