Casio CFX-9850GB PLUS User manual

CASIO
Introductory
Graphics Calculator
Workshop
Using the Casio CFX-9850GB PLUS
Casio Education Division
Ph [phone]
Fax [phone]
Email casio.ed[email protected]m.au

GETTING STARTED WITH THE CFX-9850 GB PLUS
Turning ON
•Press the AC/ON key.
When you turn your CFX 9850 on, you will see the main menu screen. Each icon on
the main menu screen stands for a MODE on the calculator.
Below is a short summary of the main purpose(s) of each mode.
RUN – The scientific calculator
STAT – For statistical calculations
MAT – To enter, and perform row/column operations upon, matrices
LIST – To manipulate lists (can also be done in STAT mode) or change
List Files.
GRAPH – To graph and analyse functions, parametric graphs and polar
graphs.
DYNA – To look at the effect of a changing constant on the graph of a
function.
TABLE – Will produce a table of values for any function.
RECUR – To produce tables and graphs from and analyse recursive
relations.
CONICS – To graph and analyse conics.
EQUA – Will solve simultaneous equations and polynomials. Also
contains an equation solver to find the value of any pronumeral in an
equation.
PRGM – Program mode. Use this mode to write programs. Stores and
executes programs also.
TVM – Time Value of Money. For financial calculations.
LINK – Allows the calculator to link to a PC or another calculator to
transfer programs and data.
CONT – Contrast. Adjusts the contrast and colour balance.
MEM – Memory. Shows memory usage and allows you to reset
individual memories or the entire calculator. Note that resetting the
calculator will delete stored data and programs.

Resetting the Calculator
Resetting the calculator serves two main purposes:
1. It clears any previous operations that the current user may not be familiar with
or want to use.
2. It returns the calculator to its initial default settings.
♦To reset the calculator, using the arrow keys highlight the MEM (memory) icon
and press the blue EXE key. To select RESET, use the down arrow followed by
EXE. Press YES (F1) followed by the MENU key to return back to the menu
screen.
The Function Keys – F-Key(s)
To use the calculator effectively, it is important to
understand how the function keys work, that is the F1 to
F6 keys. These keys actually correspond to options that
appear along the bottom of the calculator screen once a
mode has been entered. This is illustrated in the screen
shown opposite which is in the GRAPH mode. These
functions keys are continuously used and you should be
very familiar with how they work. F1 F2 F3 F4 F5 F6
Other important keys:
(-) is the change of sign key and should only be used for this purpose
The four arrow keys to move the cursor around the screen
EXE should be pressed to enter a mode and also after typing information into
the calculator
EXIT will take you back a step
MENU will take you back to the main menu

THE SCIENTIFIC CALCULATOR
The CFX-9850 GB PLUS has identical capabilities to that of a scientific calculator. It
has a keyboard almost identical to that of a scientific calculator. All those operations
performed on a scientific calculator can be accessed using the RUN mode (MENU
1). To complete a calculation, first type an expression into the command line and
press the blue EXE key to execute the command. The EXE key (located in the
bottom right hand corner) replaces the ‘=’ key on the scientific calculator.
♦The yellow SHIFT key enables the user to access the yellow (secondary)
functions located above the calculator keys.
♦Casio Scientific and Graphic Calculators use S-VPAM (Super Visually Perfect
Algebraic Method), that is ‘how you say / write it, is how you enter it’. For
example, the square root of 12 is entered by SHIFT then X2followed by 12, i.e.
√12.
♦The power (exponentiation) function is accessed using the ∧key (next to the EXIT
key. For example, 26is entered as 2 ∧6 followed by EXE.
♦The (red) ALPHA key will allow you to access the red secondary functions.
♦The F↔D key converts a fraction to a decimal or a decimal to a fraction once a
calculation has been completed (non terminating decimals are not included!).
The Run Mode
Enter into the RUN mode from the main menu by using the arrows to highlight the
RUN mode then press EXE, or from the main menu simply press 1.
Because the calculator has been reset, it has returned to its initial default settings. To
examine the default settings of the RUN mode press SHIFT then MENU (SETUP).
Notice, for example, that the default setting for an angle is currently radians. Scroll
down the screen, using the arrows, to highlight Angle. At the bottom of the screen
you have three options for Angle:
Deg (degrees), Rad (radians) and Gra (gradients)
F1 F2 F3
Press the F-key that corresponds to degrees (i.e. F1) and note that the option has
now been changed on your screen. Press the EXIT key, then enter 10cos60 and
press EXE.

Note that you have now changed the angle setting of the calculator to degrees. The
calculator will remain in degrees until you either reset the calculator or alter the
setting as you have recently done.
Memories
Results can be stored in one of twenty six variable memories by using the key
followed by any of the letters A – Z. Recall, that to access a letter first press the red
ALPHA key followed by the corresponding letter that you want to use, then press the
EXE key.
(N.B: the letters are in red and are secondary key functions).
The calculator understands the mathematical syntax, such that LB is interpreted as
L x B.
Number patterns – A.P’s and G.P’s
The last command line is automatically stored in the Independent Memory. Useful
and practical applications of this feature involve generating Arithmetic or Geometric
Progressions, generating Time Payment or Superannuation sequences.
Store the first term of the sequence by entering the number then pressing EXE. For
example, to generate an A.P enter the first term 5 EXE, then enter the common
difference + 7, then press EXE repeatedly; this will generate the A.P which has been
constructed.

GRAPHING FUNCTIONS
Enter the GRAPH mode from the main menu.
The X,θ
θθ
θ,T Key
The variable key is located just under the red ALPHA key. This key is the only key to
be used when entering a variable in an equation.
The View-Window
The view-window option displays the dimensions and scale of the axes that appear
on the calculator screen. To access this screen, press SHIFT F3. There are three
default windows that are set up for you already. These are INITIAL (F1),
TRIGONOMETRY (F2) and STANDARD (F3). The default setting is INITIAL.
Press EXIT to leave this screen.
Drawing a Function
Type into Y1 the equation .1X(X+3)(X-3) then press EXE to store the function. To
draw, press DRAW (F6).
Trace the function by pressing TRACE (SHIFT F1). By using the left and right arrows,
you can trace the graph. Use the trace function to find the roots of this equation.
G-Solve
G-Solve stands for Graph Solve. To access G-Solv
press SHIFT then F5. With G-Solve, you can find roots,
maximums, minimums, the y intercept, intersection
points, as well as perform integrations. Press F1
(ROOT) to find the first root of the equation. To access
the second and third roots, press the right arrow key.

Integration
Press G-SOLV (SHIFT F5) then F6 (the continuation key) and finally ∫dx (F3). Use
the left arrow key to set the lower limit at X=-3 then press EXE. Set the upper limit at
X=0 and press EXE.
Finding the gradient of the tangent at a point
Press SHIFT MENU to enter the SETUP of the graph mode. Highlight Derivative,
and press ON (F1). Press EXIT and DRAW (F6) then trace the function again by
pressing TRACE (SHIFT F1). This will now show the derivative at each point on the
function.
Graphing The First and Second Derivative
To graph the derivative of this function, press EXIT to allow you to type in another
function and highlight Y2. Press OPTN, CALC, d/dx (F1). Then press VARS, GRPH
(F4), Y (F1). Then type 1, X and close the brackets. Press EXE and DRAW (F6). You
can trace these graphs by pressing TRACE (SHIFT F1). To trace the graph of the
derivative, press the down arrow. It is possible to draw the derivative in a different
colour than the original function.
It is possible to draw the second derivative of the function using the same process.

Zooming and Sketching
Once you have drawn a particular function, by pressing SHIFT F2 you will activate
the Zoom option. This allows the user to zoom in or out from a particular point on the
function by a given or specified factor. It will also allow the user to zoom in on a
specific part of the graph, for example a root or point of intersection.
Again, once a function has been drawn, you can activate the Sketch option by
pressing SHIFT F4. Using this option allows us to sketch tangents, normals, inverse
functions, draw a circle with a specified radius, sketch vertical and horizontal lines
and more!
Absolute Value Graphs
To draw an absolute value function first press OPTN
followed by NUM (F5) then Abs (F1). If there is more than
one term in the function to be sketched, make sure that
brackets are used after the Abs notation.
Inequalities
From the text screen in the GRAPH mode, press TYPE (F3) then the continuation
key (F6) and the options for sketching inequalities will appear on the screen. Press
Y> (F1) and note the change at the top of the screen. Enter the equations as shown
below, draw and observe the region satisfied by the two inequalities.

Families of Functions / Restricted Domains
The GRAPH will allow us to investigate families of functions in a very purposeful and
constructive manner. For example, if a student wants to understand the effect of the
addition of a constant in a quadratic function.
The { } parentheses, secondary functions above the multiplication and division keys,
allow us to construct and draw a family of functions. To complete this investigation
make Y1 = x2+ {-2, -1, 0, 1, 2}, store and draw the function using the initial view
window. Note that all five functions will be draw on the same coordinate plane.
To restrict the domain of a function use the
‘square’ parentheses [ ].

GRAPHING FUNCTIONS
Sketching Trigonometric Functions
Before sketching a trig function you must decide whether to sketch in degrees or
radians. For the purposes of this example, it is imperative that we sketch in radians.
From the RUN mode enter the SET UP (SHIFT
MENU) and check that the Angle setting of the
calculator is set to radians. If not, scroll down using
the down arrow to Angle, then press Rad (F2).
EXIT the SET UP, press MENU and enter into the
GRAPH mode of the calculator (MENU 5). Once in the
GRAPH mode, alter the View-Window (SHIFT F3) to
the TRIG (F2) setting.
Note that the default trig setting sketches the trig
function for {x: -3π≤x ≤3π}
Press EXIT to return to the text screen. Use the functions available in the GRAPH
mode to sketch y = sin x, and find its derivative in the given domain.
To enter the ‘d/dx’ symbol press OPTN then CALC
(F2) (to access the calculus options) followed by F1
(d/dx).
You may wish to draw Y2 in a different colour. If so,
press COLR (F4) then choose the colour that you want
to use. Orange (F2) is an excellent contrast to blue or
green. To draw the two functions press DRAW (F6).
To enter the ‘Y’ symbol press VARS (variables) then
GRPH (F4) followed by Y (F1). Notice that the graph
of cos x has been drawn against the graph of sin x,
exposing the result that the first derivative of sin x w.r.t
x is actually cos x.