Reteach Absolute-Value Functions

Name
LESSON
2-9
Date
Class
Reteach
Absolute-Value Functions
The graph of the absolute-value parent function
looks like a V.
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To translate f  x    x  to a new vertex  h, k ,
use g  x    x  h   k.
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Translate f  x    x  so that the vertex is at  2, 3 .
g x    x  h   k
Write the transformation.
g  x    x  2    3 
Substitute h  2, k  3.
g x    x  2   3
Simplify.
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Graph to check:
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The vertex is  2, 3 .
The entire graph of the
parent function moves
when the vertex moves.
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Translate f  x    x  to each new vertex. Then graph the
transformation.
1. vertex  1, 2 
2.
g x    x 

g x   
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Copyright © by Holt, Rinehart and Winston.
All rights reserved.
a207c02-9_rt.indd 70
vertex  3, 1 
70
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Holt Algebra 2
12/7/05 6:27:40 PM
Name
LESSON
2-9
Date
Class
Reteach
Absolute-Value Functions (continued)
To vertically stretch or compress f x by a factor of a, use
f x r a f x .
To horizontally stretch or compress f x by a factor of b, use
1x .
f x r f __
b
Stretch the graph of f x x 1
vertically by a factor of 2.
Y
g x a f x g x 2 x 1 Substitute.
g x 2 x 2
G X
Distribute.
F X
X
Compress the graph of f x x 2 Y
1.
horizontally by a factor of __
2
1x
g x f __
b
1 x f 2x g x f ___
1
__
2
Substitute.
g x 2x 2 2x 2 Simplify.
X
Perform each transformation.
3. Stretch f x x 1 vertically by a factor of 3.
g x 3 x g x a f x ⫺ 1
g x 3 x ⫺ 3
g x 2x ⫹ 1 g x 2x ⫺ 1
4. Stretch f x 4x 1 horizontally by a factor of 2.
b 1x f
g x f __
1
__
2 x
g x 4
1
__
2
x 1
1.
5. Compress f x 4x 2 vertically by a factor of __
2
1
__
g x a f x Copyright © by Holt, Rinehart and Winston.
All rights reserved.
a207c02-9_rt.indd 71
g x 2 4x ⫺2 71
Holt Algebra 2
4/28/06 5:33:25 PM
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