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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 45

Graph the given functions, f and g, in the same rectangular coordinate system. Select integers for x, starting with -2 and ending with 2. Once you have obtained your graphs, describe how the graph of g is related to the graph of f. f(x) = |x|, g(x) = |x| − 2

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Identify the given functions: \(f(x) = |x|\) and \(g(x) = |x| - 2\). Notice that \(g(x)\) is derived from \(f(x)\) by subtracting 2 from the output values.
Create a table of values for \(x\) starting from \(-2\) to \(2\). For each \(x\), calculate \(f(x) = |x|\) and \(g(x) = |x| - 2\). For example, when \(x = -2\), \(f(-2) = |-2| = 2\) and \(g(-2) = 2 - 2 = 0\).
Plot the points for both functions on the same coordinate system. For \(f(x)\), plot points like \((-2, 2)\), \((-1, 1)\), \((0, 0)\), \((1, 1)\), and \((2, 2)\). For \(g(x)\), plot the corresponding points shifted down by 2 units, such as \((-2, 0)\), \((-1, -1)\), \((0, -2)\), \((1, -1)\), and \((2, 0)\).
Draw the graph of \(f(x) = |x|\), which is a 'V' shape with its vertex at the origin \((0,0)\). Then draw the graph of \(g(x) = |x| - 2\), which has the same 'V' shape but shifted vertically downward by 2 units.
Describe the relationship: The graph of \(g(x)\) is the graph of \(f(x)\) shifted downward by 2 units. This vertical shift is due to the subtraction of 2 in the function \(g(x) = |x| - 2\).

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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. Its graph is a V-shaped curve with the vertex at the origin (0,0), reflecting all negative inputs as positive outputs. Understanding this shape is essential for graphing and comparing transformations.
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Function Transformation - Vertical Shift

A vertical shift occurs when a constant is added or subtracted from a function, moving its graph up or down without changing its shape. For g(x) = |x| - 2, the graph of f(x) = |x| is shifted downward by 2 units, affecting the vertex position and all output values.
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Graphing Functions Using Integer Inputs

Selecting integer values for x, such as from -2 to 2, helps in plotting precise points on the coordinate plane. This method simplifies graphing by providing clear reference points to visualize the function's behavior and compare transformations between f and g.
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