Chapter 5: Problem 28
For the following exercises, find the intercepts of the functions. $$ f(x)=x^{3}+27 $$
Short Answer
Expert verified
The y-intercept is \((0, 27)\); the x-intercept is \((-3, 0)\).
Step by step solution
01
Understand the intercepts
In any function, the intercepts are the points where the graph of the function crosses the axes. The y-intercept occurs where \( x = 0 \), and the x-intercepts occur where \( f(x) = 0 \). For this function, \( f(x) = x^3 + 27 \), we need to find both the y-intercept and the x-intercepts.
02
Find the y-intercept
The y-intercept is found by setting \( x = 0 \) in the function. \[ f(0) = 0^3 + 27 = 27 \] Thus, the y-intercept is at the point \((0, 27)\).
03
Find the x-intercepts
The x-intercepts are found by setting \( f(x) = 0 \). Thus, we solve: \[ x^3 + 27 = 0 \] Rearrange it to: \[ x^3 = -27 \] Taking the cube root of both sides gives: \[ x = \sqrt[3]{-27} = -3 \]
04
Identify the x-intercept
Since there is only one real cube root of -27, the x-intercept is at the point \((-3, 0)\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Understanding the Y-Intercept
The y-intercept of a function is a key concept to understand when analyzing the graph of an equation. It describes where the graph crosses the y-axis. To find the y-intercept, set the value of x to zero and solve for the function's output.
For example, in the polynomial equation \( f(x) = x^3 + 27 \), the y-intercept can be found by evaluating \( f(0) \). This yields: \[ f(0) = 0^3 + 27 = 27 \] Therefore, the point where the graph crosses the y-axis is at
Knowing the y-intercept helps in plotting the function and understanding its overall direction.
For example, in the polynomial equation \( f(x) = x^3 + 27 \), the y-intercept can be found by evaluating \( f(0) \). This yields: \[ f(0) = 0^3 + 27 = 27 \] Therefore, the point where the graph crosses the y-axis is at
- y-intercept: \( (0, 27) \)
Knowing the y-intercept helps in plotting the function and understanding its overall direction.
Exploring the X-Intercepts
Finding x-intercepts is essential for understanding where a graph crosses the x-axis. These are the points where the output value (f(x)) is zero. To find these for the function \( f(x) = x^3 + 27 \), we need to solve the equation \( f(x) = 0 \).
This means solving: \[ x^3 + 27 = 0 \]First, rearrange the equation to: \[ x^3 = -27 \] By taking the cube root of both sides, we find: \[ x = \sqrt[3]{-27} = -3 \]This provides us with a single x-intercept at:
This means solving: \[ x^3 + 27 = 0 \]First, rearrange the equation to: \[ x^3 = -27 \] By taking the cube root of both sides, we find: \[ x = \sqrt[3]{-27} = -3 \]This provides us with a single x-intercept at:
- x-intercept: \( (-3, 0) \)
Decoding Polynomial Equations
Polynomial equations are expressions that involve variables raised to whole number powers. These equations can carry simple degrees, such as linear polynomials \( ax + b \), or more complex ones, with higher powers like cubic polynomials.
The focus equation \( f(x) = x^3 + 27 \) is a cubic polynomial with a degree of 3, signifying that the highest power of the variable x is three.
Key features of polynomial equations include:
The focus equation \( f(x) = x^3 + 27 \) is a cubic polynomial with a degree of 3, signifying that the highest power of the variable x is three.
Key features of polynomial equations include:
- High-degree terms that indicate multiple solutions
- Smooth graphs without jumps
- Predictable end behavior based on the leading term
Graphing Functions Made Easy
Graphing polynomial functions is a straightforward task once you grasp the concept of intercepts and their significance. The graph of a function represents all solutions of a polynomial equation visually. With the equation \( f(x) = x^3 + 27 \), visualize the points where it crosses the axes using the x and y intercepts discussed earlier.
Here’s a step-by-step process to graph a function easily:
Here’s a step-by-step process to graph a function easily:
- Determine the y-intercept: start by plotting the point \((0,27)\)
- Find x-intercepts: plot the point \((-3,0)\) for this particular function
- Identify key features such as symmetry or direction of end behavior
- Draw a smooth curve through these points, noting that polynomial graphs have no sharp turns