3-8-5

Analyzing a Function Used to Draw a Graph

u To determine coordinates at a particular point on a graph

Example: To graph the function y = x (x + 2)(x – 2) and determine the y-coordinate when x = 0.5, and the x-coordinate when y = 2.2

(1)Display the View Window dialog box, and then configure it with the following parameters.

xmin = –7.7,

xmax = 7.7,

xscale = 1

ymin = –3.8,

ymax = 3.8,

yscale = 1

(2)On the Graph Editor window, input and store y = x (x + 2)(x – 2) into line y1, and then tap $ to graph it.

•Make sure that only y1 is checked.

(3)To obtain the value of y for a particular x-value, tap [Analysis], [G-Solve], and then [y-Cal].

•This displays a dialog box for specifying the x-value.

(4)For this example, input 0.5 and then tap [OK].

•This moves the pointer to the location on the graph where x = 0.5, and displays the x-coordinate and y-coordinate at that location.

(5)To obtain the value of x for a particular y-value, tap [Analysis], [G-Solve], and then [x-Cal].

•This displays a dialog box for specifying the y-value.

(6)For this example, input 2.2 and then tap [OK].

•This moves the pointer to the location on the graph where y = 2.2, and displays the x-coordinate and y-coordinate at that location.

Result Screenshots

Tip

•When there are multiple results for the above procedure, press e to calculate the next value. Pressing d returns to the previous value.

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