Zeros of Functions Using the Graphing Calculator TI-Nspire

Zeros of Functions

The graphing calculator is very helpful when determining the zeros of functions
(the locations were the graph crosses the x-axis --- the zeros or roots).

Let's take a look at a couple of options for finding zeros of functions.

Using the ZERO command:

Solve:

Since this equation is set equal to zero, the zeros (roots) will be the locations where the graph crosses the x-axis (if the roots are real numbers).
1. Set f (x) = x² - 5x - 14

2. Engage the ZERO command:
, #6 Analyze Graph, #1 Zero

(lower bound) Move "pointing hand" to the left of intersection point (where the graph crosses the x-axis), and click. This will lock a location on the left of the intersection.

(upper bound) Move the hand to the right side of the intersection, and click. The right boundary will appear and the intersection point will be labeled.

3. Repeat the entire process for the second zero (root).

4. Both zeros (or roots) appear.

Window has been adjusted to
[x: 10 to -10] and [y: 5 to - 25]

Using the TRACE command:

Solve:

1. Set f (x) = x² - 5x - 14

2. Engage the TRACE command:
, #5 Trace, #1 Trace Graph

When the spider appears on the graph, use the right arrow (touch pad) to move toward a zero. Keep moving the spider until the word "zero" appears highlighted in yellow. The coordinates will appear in the lower right corner of the graph.

3. Repeat the process for the second zero (root).

4. Both zeros (or roots) appear. (7,0) and (-2,0)

Window has been adjusted to
[x: 10 to -10] and [y: 5 to - 25]

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