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EL-9900 Graphing Calculator
NotesStep & Key Operation Display
10-3
2-1
Enter the function
y =|3.5x + 4|for Y1.
Enter y = 10 for Y2.
2-2
Since the inequality you are
solving is Y1 > Y2, the solu-
tion is where the graph of Y2
is “on the bottom” and Y1 in
“on the top.”
Set up shading.
2-3
Set viewing window to “-10 < x < 10”
and “-5 < y < 50”, and view the graph.
Y= CL
MATH
+
2nd F
DRAW
WINDOW
ENTERENTER
ENTER
ENTER
10
B
1
35 4
G1
5
0
•
2nd F
2nd F
VARS
VARS
ENTER
ENTER
AA
2
1
2
-
4
➞ x = -4, y = 10
➞ x = 1.714285714
y = 9.999999999 ( Note)
The intersections are (-4, 10)
and (1.7, 10.0). The solution
is all values of x such that
x <-4 or x >1.7.
(
Note: The value of y in the
intersection of the two graphs
may not appear exactly as 10
as shown in the example, due
to an error caused by approxi-
mate calculation.)
Find the points of intersection.
Solve the inequality.
The EL-9900 shows absolute values with | |, just as written on paper, by using
the Equation editor. Graphical solution methods not only offer instructive
visualization of the solution process, but they can be applied to inequalities that
are often difficult to solve algebraically. The Shade feature is useful to solve the
inequality visually and the points of intersection can be obtained easily.
2nd F
2nd F
CALC
CALC
2
2
1
1
(
-
)
ENTER
0
(
-
)
ENTER
0
5
ENTER
5
X/
/T/n