Graphing Absolute Value Functions

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Algebra II › Graphing Absolute Value Functions

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1

Axes_1

Refer to the above figure.

Which of the following functions is graphed?

CORRECT

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Explanation

Below is the graph of :

Axes_1

The given graph is the graph of reflected in the -axis, then translated up 6 units. This graph is

, where .

The function graphed is therefore

2

Give the vertex of the graph of the function .

CORRECT

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None of the other choices gives the correct response.

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Explanation

Let

The graph of this basic absolute value function is a "V"-shaped graph with a vertex at the origin, or the point with coordinates . In terms of ,

,

or, alternatively written,

The graph of is the same as that of , after it shifts 10 units left ( ), it flips vertically (negative symbol), and it shifts up 10 units (the second ). The flip does not affect the position of the vertex, but the shifts do; the vertex of the graph of is at .

3

Which of the following absolute value functions is represented by the following graph?

CORRECT

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The equation cannot be determined from the graph.

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Explanation

The equation can be determined from the graph by following the rules of transformations; the base equation is:

The graph of this base equation is:

When we compare our graph to the base equation graph, we see that it has been shifted right 3 units, up 1 unit, and our graph has been stretched vertically by a factor of 2. Following the rules of transformations, the equation for our graph is written as:

4

Screen_shot_2014-12-24_at_3.03.30_pm

What is the equation of the above function?

CORRECT

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Explanation

The formula of an absolute value function is where m is the slope, a is the horizontal shift and b is the vertical shift. The slope can be found with any two adjacent integer points, e.g. and , and plugging them into the slope formula, , yielding . The vertical and horizontal shifts are determined by where the crux of the absolute value function is. In this case, at , and those are your a and b, respectively.

5

Axes_1

Refer to the above figure.

Which of the following functions is graphed?

CORRECT

0

0

0

0

Explanation

Below is the graph of :

Axes_1

The given graph is the graph of reflected in the -axis, then translated left 2 units (or, equivalently, right units. This graph is

, where .

The function graphed is therefore

6

Axes_1

Refer to the above figure.

Which of the following functions is graphed?

CORRECT

0

0

0

The correct answer is not given among the other responses.

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Explanation

Below is the graph of :

Axes_1

The given graph is the graph of translated by moving the graph 7 units left (that is, unit right) and 2 units down (that is, units up)

The function graphed is therefore

where . That is,

7

Give the vertex of the graph of the function .

CORRECT

0

0

0

None of the other choices gives the correct response.

0

Explanation

Let

The graph of this basic absolute value function is a "V"-shaped graph with a vertex at the origin, or the point with coordinates . In terms of ,

The graph of this function can be formed by shifting the graph of left 6 units ( ) and down 7 units (). The vertex is therefore located at .