Chapter 3: Problem 180
For the following exercises, find the intercepts of the functions. $$f(x)=x^{3}+27$$
Short Answer
Expert verified
Y-intercept is (0, 27); X-intercept is (-3, 0).
Step by step solution
01
Understand Intercepts
Intercepts are the points where the graph of a function intersects the axes. In this exercise, we will focus on the y-intercept and x-intercepts of the function. - **Y-intercept**: This is where the graph intersects the y-axis, which happens when \(x = 0\).- **X-intercept(s)**: This is where the graph intersects the x-axis, which happens when \(f(x) = 0\).
02
Find the Y-intercept
To find the y-intercept, substitute \(x = 0\) into the function \(f(x) = x^3 + 27\).\[f(0) = 0^3 + 27 = 27\]The y-intercept is therefore at the point \((0, 27)\).
03
Find the X-intercept(s)
To find the x-intercept(s), set the function equal to zero and solve for \(x\):\[0 = x^3 + 27\]We can rewrite the equation by moving \(27\) to the other side:\[x^3 = -27\]Taking the cube root of both sides gives:\[x = \sqrt[3]{-27} = -3\]Thus, the x-intercept is at the point \((-3, 0)\).
04
Summarize the Intercepts
From the calculations, the y-intercept is at \((0, 27)\) and the x-intercept is at \((-3, 0)\). These points represent where the function \(f(x) = x^3 + 27\) crosses the y-axis and x-axis respectively.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
y-intercept
The y-intercept of a function is a point where the graph intersects the y-axis. This point occurs when the value of the independent variable, often denoted as \(x\), is zero. Thus, to find the y-intercept, we simply substitute \(x = 0\) into the given function and solve for \(f(x)\) as follows:
In real-world contexts, this point can represent the initial value or starting point of a situation being modeled by the function.
- For a polynomial function like \(f(x) = x^3 + 27\), plug \(x = 0\) to get \(f(0) = 0^3 + 27 = 27\). This calculation shows that the graph crosses the y-axis at the point \((0, 27)\).
In real-world contexts, this point can represent the initial value or starting point of a situation being modeled by the function.
x-intercepts
The x-intercepts of a function are points where its graph crosses the x-axis. This occurs when the output of the function, \(f(x)\), is zero. To find x-intercepts, set \(f(x) = 0\) and solve for \(x\).
- For the polynomial function \(f(x) = x^3 + 27\), we set up the equation as \(0 = x^3 + 27\). Simplifying, we get \(x^3 = -27\).
- The solution to this equation is found by taking the cube root of both sides: \(x = \sqrt[3]{-27} = -3\).
polynomial functions
Polynomial functions are expressions that involve sums of powers of a variable with coefficients. They take the general form \(a_nx^n + a_{n-1}x^{n-1} + ... + a_1x + a_0\), where each \(a_i\) is a constant coefficient, and \(x\) is raised to whole number powers.
- In our example, \(f(x) = x^3 + 27\), it's a polynomial function of degree 3 because the highest power of \(x\) is 3.
- This means the graph of this polynomial will have a characteristic shape that can include up to three x-intercepts, depending on the particular coefficients and constants.
- The function \(f(x)\) will also exhibit a smooth and continuous curve, dictated by the degree and the specific terms involved.