EL-9900 Graphing Calculator
NotesStep & Key Operation Display
= 0.75 , = 0 .75
10-4
2-2
Is |x + y| = |x| +|y|? Think about
this problem according to the cases
when x or y are positive or negative.
If x
≥
0 and y
≥
0
[e.g.; (x, y) = (2,7)]
If x
≤
0 and y
≥
0
[e.g.; (x, y) = (-2, 7)]
If x
≥
0 and y
≤
0
[e.g.; (x, y) = (2, -7)]
If x
≤
0 and y
≤
0
[e.g.; (x, y) = (-2, -7)]
|x +y| = |2 + 7| = 9
|x|+|y| = |2| + |7| = 9
➞|x + y| = |x| + |y|.
|x +y| = |-2 + 7| = 5
|x|+|y| = |-2| + |7| = 9
➞|x + y| ≠ |x| + |y|.
|x +y| = |2-7| = 5
|x|+|y| = |2| + |-7| = 9
➞|x + y| ≠ |x| + |y|.
|x +y| = |-2-7| = 9
|x|+|y| = |-2| + |-7| = 9
3-1
Evaluate . Evaluate .
3-2
Is |x /y| = |x|/|y|?
Think about this problem according
to the cases when x or y are positive
or negative.
If x
≥
0 and y
≥
0
[e.g.; (x, y) = (2,7)]
If x
≤
0 and y
≥
0
[e.g.; (x, y) = (-2, 7)]
If x
≥
0 and y
≤
0
[e.g.; (x, y) = (2, -7)]
If x
≤
0 and y
≤
0
[e.g.; (x, y) = (-2, -7)]
|x /y| = |2/7| = 2/7
|x|/|y| = |2| /|7| = 2/7
➞|x /y| = |x| / |y|
|x /y| = |(-2)/7| = 2/7
|x|/|y| = |-2| /|7| = 2/7
➞|x /y| = |x| / |y|
|x /y| = |2/(-7)| = 2/7
|x|/|y| = |2| /|-7| = 2/7
➞|x /y| = |x| / |y|
|x /y| = |(-2)/-7| = 2/7
|x|/|y| = |-2| /|-7| = 2/7
➞|x /y| = |x| / |y|
The statement is true for all y ≠ 0.
The EL-9900 shows absolute values with | |, just as written on paper, by using
the Equation editor. The nature of arithmetic of the absolute value can be
learned through arithmetical operations of absolute value functions.
6-9
1+3
6-9
1+3
6-9
1+3
6-9
1+3
6-9
1+3
6-9
1+3
➞ =
➞|x + y| = |x| + |y|.
Therefore |x +y|=|x|+|y|when x
≥
0 and y
≥
0,
and when x
≤
0 and y
≤
0.
CL
ENTER
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MATH
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