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Step & Key Operation Display
EL-9900 Graphing Calculator
Notes
4-1
2-2
View both graphs.
Notice that the addition of 2 moves
the basic y =
x
2
graph up two units
and the addition of - 2 moves the
basic graph down two units on
the y-axis. This demonstrates the
fact that adding k (>0) within the standard form y = a (x -
h)
2
+ k will move the basic graph up k units and placing k
(<0) will move the basic graph down k units on the y-axis.
3-2
View both graphs.
Notice that the multiplication of
2 pinches or closes the basic
y = x
2
graph. This demonstrates
the fact that multiplying an a
(> 1) in the standard form
y = a
(x - h)
2
+ k
will pinch or close
the basic graph.
4-1
Change the equation in Y2 to
y = -2x
2
.
Notice that the multiplication of
-2 pinches or closes the basic
y =
x
2
graph and flips it (reflects
it) across the x-axis. This dem-
onstrates the fact that multiply-
ing an a (<-1) in the standard form y = a (x - h)
2
+ k
will pinch or close the basic graph and flip it (reflect
it) across the x-axis.
Change the equation in Y2 to y =
x
2
+2.
2-1
3-1
Change the equation in Y2 to y = 2
x
2
.
The EL-9900 allows various quadratic equations to be graphed easily. Also the
characteristics of quadratic equations can be visually shown through the
relationship between the changes of coefficient values and their graphs, using
the Substitution feature.
4-2
View both graphs.
2nd F
GRAPH
Y=
SUB
2
0
ENTER ENTER
GRAPH
Y=
2nd F SUB
2
0
ENTER
ENTER
GRAPH
Y=
2nd F
SUB
(
-
)
2
ENTER