HP 39gs, Руководство пользователя

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Choosing the level
GRAPH mode
27
T
T
H
H
E
E
Q
Q
U
U
A
A
D
D
E
E
X
X
P
P
L
L
O
O
R
R
E
E
R
R
T
T
E
E
A
A
C
C
H
H
I
I
N
N
G
G
A
A
P
P
L
L
E
E
T
T
Rather than being a multi-purpose aplet, this is a teaching aplet specialized to the single use of exploring
graphs of quadratics. As such it does not have the normal
SYMB
,
NUM
and
PLOT
views, but only a single
multi-purpose view.
Objectives
2 =
(
+ Using the Quadratic Explorer aplet, the student will investigate the behavior of the graph of
y a x h
)
+
v
as the values of a , h and v change. This can be done both by manipulating the equation and seeing the
change in the graph, and by manipulating the graph and seeing the change in the equation.
Press to see the main screen of the aplet, shown right. This aplet
has only the one screen, rather than the usual
PLOT
,
SYMB
and
NUM
views. If the aplet has been used before then it may be necessary to
press the screen key to go back to the opening view.
The first choice made by the user should be the . The default
level is that of Y=a(X+h) 2 +v , which allows the student to change all
parameters at once. By having the student choose the levels of Y=aX
2
,
Y=(x+h) 2 or Y=X 2 +v, the teacher can confine the study to the effects of
only one coefficient at a time if desired.
The default state for the aplet is to be in mode. In this mode the
student uses the keys listed below to control the appearance of the
graph, with these changes reflected automatically in the two equations
on the right half of the screen. The original y=x 2 graph is kept on the
screen (dotted) for comparison and a grid is supplied to allow the user to
see movement more clearly.
The control keys (listed onscreen) are:
move the graph in the obvious way.
and cycle the value of ‘a’ in y=a(x+h)
2
+v through
the values 0.1, 0.2, 0.3, 0.5, 1, 2 & 5. No other
values are possible.
(the ‘negative’ key) changes the sign on the
‘a’ coefficient turning the graph upside down.
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