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Ch. 2 - Functions and Graphs
Blitzer - College Algebra 8th Edition
Blitzer8th EditionCollege AlgebraISBN: 9780136970514Not the one you use?Change textbook
Chapter 3, Problem 90

Begin by graphing the absolute value function, f(x) = |x|. Then use transformations of this graph to graph the given function. g(x) = -|x + 4| +2

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Start with the base graph of the absolute value function, f(x) = |x|. This graph is a V-shaped graph with its vertex at the origin (0, 0), opening upwards.
Identify the transformation inside the absolute value: x + 4. This represents a horizontal shift. Specifically, the graph of |x| is shifted 4 units to the left because of the +4 inside the absolute value.
Next, consider the negative sign in front of the absolute value, -|x + 4|. This reflects the graph of |x + 4| across the x-axis, causing the V-shape to open downwards instead of upwards.
Now, account for the +2 outside the absolute value. This represents a vertical shift. The entire graph of -|x + 4| is shifted 2 units upward.
Combine all the transformations: Start with the base graph of |x|, shift it 4 units to the left, reflect it across the x-axis, and finally shift it 2 units upward. Plot the resulting graph to visualize g(x) = -|x + 4| + 2.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Absolute Value Function

The absolute value function, denoted as f(x) = |x|, outputs the non-negative value of x. This function has a V-shaped graph that opens upwards, with its vertex at the origin (0,0). Understanding this function is crucial as it serves as the foundation for applying transformations to graph other functions.
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Transformations of Functions

Transformations involve shifting, reflecting, stretching, or compressing the graph of a function. For example, adding a constant inside the absolute value affects horizontal shifts, while adding outside affects vertical shifts. In the function g(x) = -|x + 4| + 2, the transformations include a horizontal shift left by 4 units, a reflection across the x-axis, and a vertical shift up by 2 units.
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Graphing Techniques

Graphing techniques involve plotting points and understanding how transformations affect the shape and position of a graph. For the function g(x), one must first graph f(x) = |x|, then apply the identified transformations systematically. This process helps visualize the changes and accurately represent the new function on a coordinate plane.
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Graphs and Coordinates - Example