EL-9600/9400 Graphing Calculator
8-4
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Choose viewing windows “-5< x <50,” and “-10< y <10” using Rapid Window feature to solve Q1.
*
*
*
Before
Start
Notes
Step & Key Operation
(When using EL-9600)
*Use either pen touch or cursor to operate.
Display
(When using EL-9600)
Solving Absolute Value Inequalities
To solve an inequality means to find all values that make the inequality true. Absolute value
inequalities are of the form |
f
(
x
)|<
k,
|
f
(
x
)|
≤
k,
|
f
(
x
)|>
k, or
|
f
(
x
)|
≥
k.
The graphical
solution to an absolute value inequality is found using the same methods as for normal
inequalities. The first method involves rewriting the inequality so that the right-hand-side of
the inequality is 0 and the left-hand-side is a function of
x.
The second method involves
graphing each side of the inequality as an individual function.
Solve absolute value inequalities in two methods.
Example
1
-
2
Enter
y =
|20 - | - 8 for Y1.
*
*
*
*
1
-
1
Rewrite the equation.
|20 - |< 8
➞
|20 - | - 8 < 0.
1
-
3
View the graph, and find the
x
-intercepts.
*
➞
x
= 10,
y
= 0
*
➞
x
= 23.33333334
y
= 0.00000006 ( Note)
The intersections with the
x-
axis are (10, 0) and (23.3, 0)
( Note: The value of
y
in the
x
-intercepts may not appear
exactly as 0 as shown in the
example, due to an error
caused by approximate calcu-
lation.)
○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○
1
-
4
Solve the inequality.
Since the graph is below the
x
-axis for
x
in between the
two
x
-intercepts, the solution
is 10 <
x
< 23.3.
6
x
5
6
x
5
1.
Solve 20 - < 8 by rewriting the inequality so that the right-hand side of
the inequality is zero.
2.
Solve 3.5
x
+ 4 > 10 by shading the solution region.
6
x
5
WINDOW
EZ
3
3
3
ENTER
ENTER
ENTER
GRAPH
2nd F CALC
2nd F CALC
B
1
2
0
6
8
1
5
5
Y=
MATH
—
—
a/b
6
x
5
X
/
/
T
/
n
HB1.DocD.
98.10.1, 6:11 PM
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