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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 115

Begin by graphing the cube root function, f(x) = ∛x. Then use transformations of this graph to graph the given function. -∛(x+2)

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Step 1: Begin by understanding the parent function f(x) = ∛x. The cube root function is symmetric about the origin and passes through points such as (0, 0), (1, 1), (-1, -1), (8, 2), and (-8, -2). Graph this parent function as the base graph.
Step 2: Analyze the transformation inside the cube root function. The term (x + 2) indicates a horizontal shift. Since it is (x + 2), the graph of the parent function will shift 2 units to the left.
Step 3: Next, consider the negative sign in front of the cube root function, -∛(x + 2). This negative sign reflects the graph across the x-axis. Every y-value of the graph will be multiplied by -1, flipping the graph vertically.
Step 4: Combine the transformations. First, shift the graph of f(x) = ∛x two units to the left, and then reflect the resulting graph across the x-axis.
Step 5: Plot the transformed graph by applying the transformations to key points of the parent function. For example, the point (0, 0) remains unchanged, (1, 1) becomes (-1, -1), and (-1, -1) becomes (-3, 1). Continue this process for other key points to complete the graph.

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Key Concepts

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

Cube Root Function

The cube root function, denoted as f(x) = ∛x, is a type of radical function that returns the number whose cube is x. It is defined for all real numbers and has a characteristic S-shaped curve that passes through the origin (0,0). Understanding its basic shape and properties is essential for applying transformations.
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Graph Transformations

Graph transformations involve shifting, reflecting, stretching, or compressing the graph of a function. For the function -∛(x+2), the graph of f(x) = ∛x is first shifted left by 2 units due to the (x+2) term, and then reflected across the x-axis because of the negative sign. Mastery of these transformations allows for accurate graphing of modified functions.
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Intro to Transformations

Reflection Across the X-Axis

Reflection across the x-axis is a transformation that flips the graph of a function over the x-axis. This means that for every point (x, y) on the original graph, the reflected point will be (x, -y). In the context of the function -∛(x+2), this reflection changes the sign of the output values, resulting in a graph that is inverted compared to the original cube root function.
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