Casio RM-9850GA PLUS Instrukcja Użytkownika Pobierz pdf (Strona 3)

Graphing on the Casio cfx-9850G Plus

1. DEFINING A FUNCTION

To graph a function, you must first define the function. Press MENU 5 to access GRAPH mode and the

list of up to 20 functions. If some functions are already defined, use and to access them and then

F2 (DEL) F1 to delete them before you start.

The X.θ.T key enters the variable (X), and the other keys are used in the usual way. Standard

algebraic syntax is used, so multiplication signs are optional. For example, to enter the function

f(x) = x

– 3x + 1, use and to choose a space, then press X.θ.T X.θ.T EXE .

Once a function is defined, it will be graphed on the current window settings by F6 (DRAW).

(A small square at upper right shows the calculator is working.)

To see the graph on a convenient window, press SHIFT F3 and then F1 (INIT) EXIT . For the

INIT screen, x- and y-axis scales are equal and each pixel represents 0.1 units.

Press F6 (G–T) to return to the function list if you want.

2. READING AND CHANGING THE SCREEN

If you press the SHIFT F3 (Viewing Window) key, you will see the current information about the x and

y axes, which also helps interpreting the screen. The values of Xscale and Yscale determine the tick marks

on the axes. Change the values of Xmin, Xmax, Ymin and Ymax by overwriting them, followed by EXE .

Note shortcuts with F1 , F2 and F3 . Use and to move between values. Press EXIT when done.

Press SHIFT MENU to access SET UP for Graph mode. Many choices are available to customise the

calculator. E.g., notice the effect of turning on the Grid. Graph Func shows the definitions of functions on

the screen, while Draw Type allows for discrete points to be plotted or connected.

3. TRACING A GRAPH

A graph may be traced using the SHIFT F1 (TRACE) key. A flashing cursor (a plus sign) appears on the

graph, and its coordinates appear at the bottom of the screen. This can be moved to left or right along

the graph using or . Move to the smallest root to see x ≈ -1.9.

Use and to move between graphs when there is more than one.

4. ZOOMING IN AND OUT

To get a more accurate view of part of the graph, we can ‘zoom in’, which is rather like using a

magnifying glass; or we can see a bigger picture by ‘zooming out’. Press SHIFT F2 (ZOOM) to access

the zoom menu, then F3 (IN) to zoom in on the cursor point. Notice how zooming in makes curves

‘straighter’. By repeating the process a few times, perhaps moving the cursor a little each time, a rather

accurate approximation to the root at x ≈ -1.879 can be found. Note that F4 (OUT) zooms out, undoing

the zooming in. Other zoom commands are available, some after pressing F6 ; e.g., return to the

original screen with (ORIG), the previous screen with (PRE) and equalise the scales on the axes with

(SQR). Check settings with SHIFT F3 (V

WINDOW).

5. BOX ZOOMING

A particular part of the graph can be magnified by using the ‘box’ method. First press F1 (BOX) in the

Zoom menu. Then move the cursor to a point to the left of and above the part of the graph you wish to

magnify. Press EXE to confirm your choice. Now use the and keys to move to the right and

below the parts of interest. (A rectangular ‘box’ will be formed on the screen as you do this.) When the

appropriate part is boxed, press EXE . Repeat this procedure to find the largest root of f, at x ≈ -1.879.

6. LEAVING THE GRAPH SCREEN

RUN mode can be accessed at any time by pressing MENU 1. Note also that pressing X.θ.T EXE will

read memory X, which contains the current x-coordinate of the cursor. Similarly EXE will read

memory Y, which contains the current y-coordinate of the cursor. These memories are changed

continuously by graphing. Pressing SHIFT F6 in RUN mode will show the graph screen, but press

MENU 5 instead if you want to do more than just look at the graphs.

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