Download Calculator Notes for the Casio fx-9750G Plus and CFX

DA2_FX9850GB_07.qxd 12/30/05 10:03 AM Page 45
CHAPTER 7
Calculator Notes for the fx-9750G Plus
and CFX-9850GC Plus
Note 7A • Function Notation
Functions are entered from GRAPH mode into the Y screen and are
referred to by name as Y1, Y2, . . . , Y19, Y20.
To evaluate a function for a particular x-value, for example, Y1 when x 4,
from RUN mode, press 4 → ,, EXE to assign a value of 4 to x. Then press
VARS F4 (GRPH) F1 (Y) 1 EXE to see the value of Y1.
Note 7B • Some Functions
To use the command for squaring, enter a number on the Run screen and
press x2 EXE .
To use the command for square root, press
Then, enter a number and press EXE .
SHIFT [ ]
on the Run screen.
To use the command for sum of a list, from RUN mode press
OPTN F1 (LIST) F6 F6 F1 (Sum). Then press SHIFT [{] and enter the numbers
in the list separated by commas. Close the braces and press EXE .
Alternately, enter numbers into a list, say List 1, from either RUN or LIST.
(See Note 1B.) Then, on the Run screen, enter “sum List 1” by pressing
OPTN F1 (LIST) F6 F6 F1 (Sum) F6 F1 (List) 1 and EXE .
The command for random number generates a random ten-digit
decimal number between 0 and 1. From RUN mode, press
OPTN F6 F3 (PROB) F4 (Ran#) EXE .
©2007 Key Curriculum Press
Discovering Algebra Calculator Notes for the Casio fx-9750G Plus and CFX-9850GC Plus
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fx-9750G Plus and CFX-9850GC Plus
Note 7C • Absolute Value
To find the absolute value of a number, from the Run screen, press
OPTN F3 (CPLX) F2 (Abs). Then, enter a number and press EXE .
Note 7D • Friendly Windows
When you trace a function or locate a point on the screen, you often see
long, “ugly” decimal values for the coordinates of your points. Sometimes,
however, the values are “nice, friendly” values like 2.4 or 4.84, or repeating
decimals like 4.3333333.
When the proper values are set for Xmin and Xmax in the View Window
screen, the coordinate values of your points will be “friendly” numbers
for most functions. This is because the calculator screen is made of tiny
square dots called pixels, and when you move horizontally across the
screen, the x-coordinate changes by one pixel with each trace step. The
total number of pixels across the screen is 127; in other words, it takes
126 steps to get across. When 126 is either equal to or a multiple of the
breadth of the domain Xmax Xmin, the window will be friendly. For
example, if Xmin 0 and Xmax 126 or Xmin 1 and Xmax 13.6,
the window will be friendly. (Note: The y-coordinate is calculated by
evaluating the function for the x-coordinate. So if the coefficients in
a function are irrational, the y-coordinates will not be nice even in a
friendly window.)
Two Friendly Square Windows
If you press SHIFT [V-Window] F1 (INIT), you get a special type of small
friendly window called a friendly square window. It is friendly because it has
the view window values [6.3, 6.3, 1, 3.1, 3.1, 1]. It is square because the
horizontal and vertical scales on the screen are equal in size. In a square
window, circles appear symmetric and round, and the line y x makes a
45-degree angle with both axes. A square window is often the preferred
window to use because it displays no visual distortion. However, this
window, [6.3, 6.3, 1, 3.1, 3.1, 1], is sometimes too small to show much
of the graph.
[6.3, 6.3, 1, 3.1, 3.1, 1]
(continued)
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Note 7D • Friendly Windows (continued)
fx-9750G Plus and CFX-9850GC Plus
To see more of the graph in the window, you can double the Xmin, Xmax,
Ymin, and Ymax values, [12.6, 12.6, 1, 6.2, 6.2, 1]. This square window is
referred to as the friendly window with a factor of 2.
[12.6, 12.6, 1, 6.2, 6.2, 1]
The friendly window with a factor of 2 is often a convenient window to use.
To save it and recall it quickly, follow these steps.
a. First, enter the values [12.6, 12.6, 1, 6.2, 6.2, 1] into your View
Window screen.
b. Then, from the View Window screen, press F4 (STO) F1 (V-W1).
Note: Up to five more windows can be stored by using the other
function keys.
c. The next time you need this window, say for the graph of y x 2,
press SHIFT [V-Window] F5 (RCL) F1 (V-W1).
[10, 10, 1, 10, 10, 1]
[12.6, 12.6, 1, 6.2, 6.2, 1]
Other Friendly Square Windows
To assure that a window is square, the size of a horizontal step, called ∆x,
must equal the size of a vertical step, called ∆y. ∆x is the step size of the
trace. In the square window [6.3, 6.3, 1, 3.1, 3.1, 1], ∆x is 0.1. In the
square window [12.6, 12.6, 1, 6.2, 6.2, 1], ∆x is 0.2.
Values for origin-centered friendly square windows are
[63 ∆x, 63 ∆x, 1, 31 ∆y, 31 ∆y, 1]. For example, if ∆x
and ∆y equal 0.3, then . . .
(continued)
©2007 Key Curriculum Press
Discovering Algebra Calculator Notes for the Casio fx-9750G Plus and CFX-9850GC Plus
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Note 7D • Friendly Windows (continued)
fx-9750G Plus and CFX-9850GC Plus
First-quadrant friendly square window values are
[0, 126 ∆x, 1, 0, 62 ∆y, 1]. Again, if ∆x and ∆y equal 0.3, then . . .
[0, 37.8, 1, 0, 18.6, 1]
Friendly Windows That Are Not Square
The Ymin and Ymax values of a friendly window can be changed to show
a larger or smaller range. The graph will look distorted and it will no
longer be square, but this might be necessary to see more of the graph.
For example, the graph of y x 2 in the friendly square window
[12.6, 12.6, 1, 6.2, 6.2, 1] runs off the top of the graph for x-coordinates
greater than 2.4. If you want to see more of the graph, change the window
to [12.6, 12.6, 1, 10, 100, 10]. This is a friendly window because the
coordinates are still nice, but it is not square.
[12.6, 12.6, 1, 6.2, 6.2, 1]
[12.6, 12.6, 1, 10, 100, 10]
You can also see more of a graph without first changing the view window
settings. Without using the trace option, press an arrow key to automatically
scroll the graph in any direction. As you scroll, the view window settings
change to reflect the current screen.
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Discovering Algebra Calculator Notes for the Casio fx-9750G Plus and CFX-9850GC Plus
©2007 Key Curriculum Press