Texas Instruments TI-82 Getting Started page 16

Technology Tip: The TI-82 remembers the window it displayed before a zoom. So, if you should zoom in
too much and lose the curve, press ZOOM
to execute a series of zooms but then return to a particular window, press ZOOM
the current window's dimensions. Later, press ZOOM
I.2.7 Value: Graph y
the value of this function for any given (between the Xmin and Xmax values).
Press 2nd CALC to display the CALCULATE menu (see Figure I.45), then press 1 [value]. The graph of
the function is displayed and you are prompted to enter a value for
entered and its corresponding
point 1, 3 on the graph (see Figure I.46).
Figure I.45: CALCULATE menu
Note that if you have more than one graph on the screen, the upper right corner of the TI-82 screen will
display the numeral corresponding to the equation of the function in the Y= list whose value is being
calculated. Press the up
entered x- value.
I.2.8 Relative Minimums and Maximums: Graph
dow (Figure I.12). This function appears to have a relative minimum near
near x 1. You may zoom and trace to approximate these extreme values.
First trace along the curve near the relative minimum. Notice by how much the values and values change
as you move from point to point. Trace along the curve until the
so that you are as close as possible to the relative minimum, and zoom in (press ZOOM 2 ENTER or use a
zoom box). Now trace again along the curve and, as you move from point to point, see that the coordinates
change by smaller amounts than before. Keep zooming and tracing until you find the coordinates of the
relative minimum point as accurately as you need them, approximately
I-16
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1 [ZPrevious] to go back to the window before. If you want
3
x 4x in the standard viewing window (Figure I.12). The TI-82 can calculate
x
y- value are shown at the bottom of the screen and the cursor is located at the
or down arrow key to move the cursor vertically between functions at the
−10
Figure I.47: Finding a minimum
3 [ZoomRcl] to recall the stored window.
Press 1 ENTER. The
x.
−10
−10
Figure I.46: Finding a value
3
y x 4x once again in the standard viewing win-
x
y- coordinate is as small as you can get it,
1.15,
10
10
−10
2 [ZoomSto] to store
x- value you
10
10
1 and a relative maximum
x- y-
3.08 .
TI-82 Graphics Calculator