Chapter 3: Problem 9
Sketch the graph of the function by first making a table of values. $$ g(x)=x^{3}-8 $$
Short Answer
Expert verified
Plot points for x values, draw a smooth cubic curve through them.
Step by step solution
01
Choose Values for x
Select a few values for \( x \) to plug into the function. Common choices are to use both negative and positive integers, and zero. This helps in visualizing different parts of the curve. Let's choose \( x = -2, -1, 0, 1, 2 \).
02
Calculate Corresponding g(x) Values
Plug the chosen \( x \) values into the function \( g(x) = x^3 - 8 \) to find the corresponding \( g(x) \) values.\\( g(-2) = (-2)^3 - 8 = -8 - 8 = -16 \)\\( g(-1) = (-1)^3 - 8 = -1 - 8 = -9 \)\\( g(0) = (0)^3 - 8 = 0 - 8 = -8 \)\\( g(1) = (1)^3 - 8 = 1 - 8 = -7 \)\\( g(2) = (2)^3 - 8 = 8 - 8 = 0 \)
03
Create a Table of Values
Organize the calculated \( x \) and \( g(x) \) values into a table for clarity.\\[\begin{array}{c|c}x & g(x) \\hline-2 & -16 \-1 & -9 \0 & -8 \1 & -7 \2 & 0 \\end{array}\]
04
Plot the Points on a Graph
Plot the points \((-2, -16), (-1, -9), (0, -8), (1, -7), (2, 0)\) on the coordinate plane. Each point is represented as a dot on the plane.
05
Sketch the Graph
Draw a smooth curve through the plotted points. Since the function \( g(x) = x^3 - 8 \) is a cubic function, expect the curve to have an S-shape. It should decrease towards negative infinity on the left and increase towards positive infinity on the right.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Cubic Functions
A cubic function is a polynomial function of degree three. The general form is given as \( f(x) = ax^3 + bx^2 + cx + d \), where \( a \), \( b \), \( c \), and \( d \) are constants and \( a eq 0 \). The defining characteristic of a cubic function is its highest exponent, which is three, indicating the degree of the polynomial. Cubic functions can have various shapes, but they typically appear as an "S-shaped" curve. This is due to the nature of the cubic term, which dominates the behavior of the function at extreme values of \( x \). The major characteristics include:
- Direction: The curve can increase or decrease at both ends, creating a wave-like pattern.
- Turning Points: Cubic functions can have up to two turning points where the function changes direction.
- Inflection Point: They usually have one inflection point—a spot where the curvature changes from concave up to concave down or vice versa.
Table of Values
Creating a table of values is a helpful strategy for understanding how a function behaves over a specific range of \( x \) values. By choosing specific points, you can see how the function transitions and starts to take on its curve shape. To start, you select several \( x \) values that span both negative and positive numbers, including zero. This range allows you to observe different aspects of the graph:
- Choose x-values: Opt for integer values unless the problem requires otherwise. For our exercise: \( x = -2, -1, 0, 1, 2 \).
- Calculate y-values: Substitute these \( x \) values into the function to find corresponding \( g(x) \) values like \(-16, -9, -8, -7, 0\).
Function Graphing
Graphing functions is an essential math skill that involves plotting points on a coordinate plane. You begin by using the table of values you created, which guides the placement of points on the graph. Here is a quick guide to function graphing:
- Plot Points: Take the \((x, g(x))\) pairs from the table and mark these coordinates on the graph. For example, the points \((-2, -16), (-1, -9), (0, -8), (1, -7), (2, 0)\).
- Connect the Dots: Use a smooth and continuous curve to join the plotted points. Cubic graphs should gently swerve in an S-shape.
Coordinate Plane
The coordinate plane is a two-dimensional surface where we plot functions, consisting of two perpendicular axes, \( x \) (horizontal) and \( y \) (vertical). Each point on this plane is defined by a pair of numeric coordinates \((x, y)\), which dictates its position relative to these axes. Here are some key facets of the coordinate plane:
- Axes: The \( x \)-axis and \( y \)-axis split the plane into four quadrants where points can be plotted.
- Quadrants: The plane is divided clockwise into four areas. Points in the top right have both positive \( x \) and \( y \) values, while those below the \( x \)-axis have negative \( y \) values.