Understanding Absolute Maximum and Minimum Values

Oct 13, 2025 by wbrum.org 16 views

Finding Absolute Maximum and Minimum Values of a Quadratic Function

In this article, we will explore the concept of absolute maximum and minimum values of a quadratic function. We will use the given function $f(x) = 5x^2 - 2x + 8$ on the interval $0 \leq x \leq 7$ to demonstrate the process of finding these values using calculus.

Understanding Absolute Maximum and Minimum Values

The absolute maximum value of a function on a given interval is the largest value that the function attains on that interval. Similarly, the absolute minimum value is the smallest value that the function attains on that interval.

Step 1: Find the Critical Points

To find the absolute maximum and minimum values of the function, we need to find the critical points. Critical points are the values of $x$ where the derivative of the function is equal to zero or undefined.

Finding the Derivative

To find the derivative of the function $f(x) = 5x^2 - 2x + 8$ , we will use the power rule of differentiation.

f'(x) = \frac{d}{dx} (5x^2 - 2x + 8)

f'(x) = 10x - 2

Finding the Critical Points

To find the critical points, we need to set the derivative equal to zero and solve for $x$ .

10x - 2 = 0

10x = 2

x = \frac{2}{10}

x = \frac{1}{5}

Step 2: Evaluate the Function at the Critical Points and the Endpoints

Now that we have found the critical points, we need to evaluate the function at these points and the endpoints of the interval.

Evaluating the Function at the Critical Points

We will evaluate the function at the critical point $x = \frac{1}{5}$ .

f\left(\frac{1}{5}\right) = 5\left(\frac{1}{5}\right)^2 - 2\left(\frac{1}{5}\right) + 8

f\left(\frac{1}{5}\right) = 5\left(\frac{1}{25}\right) - \frac{2}{5} + 8

f\left(\frac{1}{5}\right) = \frac{1}{5} - \frac{2}{5} + 8

f\left(\frac{1}{5}\right) = -\frac{1}{5} + 8

f\left(\frac{1}{5}\right) = \frac{-1 + 40}{5}

f\left(\frac{1}{5}\right) = \frac{39}{5}

Evaluating the Function at the Endpoints

We will evaluate the function at the endpoints of the interval $x = 0$ and $x = 7$ .

f(0) = 5(0)^2 - 2(0) + 8

f(0) = 0 - 0 + 8

f(0) = 8

f(7) = 5(7)^2 - 2(7) + 8

f(7) = 5(49) - 14 + 8

f(7) = 245 - 14 + 8

f(7) = 239

Step 3: Compare the Values

Now that we have evaluated the function at the critical points and the endpoints, we need to compare the values to find the absolute maximum and minimum values.

Comparing the Values

We will compare the values of the function at the critical points and the endpoints.

f\left(\frac{1}{5}\right) = \frac{39}{5}

f(0) = 8

f(7) = 239

From the comparison, we can see that the absolute maximum value of the function is $f(7) = 239$ and the absolute minimum value is $f\left(\frac{1}{5}\right) = \frac{39}{5}$ .

In this article, we have used calculus to find the absolute maximum and minimum values of the quadratic function $f(x) = 5x^2 - 2x + 8$ on the interval $0 \leq x \leq 7$ . We have found the critical points, evaluated the function at these points and the endpoints, and compared the values to find the absolute maximum and minimum values. The absolute maximum value is $f(7) = 239$ and the absolute minimum value is $f\left(\frac{1}{5}\right) = \frac{39}{5}$ .
Q&A: Finding Absolute Maximum and Minimum Values of a Quadratic Function

In our previous article, we explored the concept of absolute maximum and minimum values of a quadratic function. We used the given function $f(x) = 5x^2 - 2x + 8$ on the interval $0 \leq x \leq 7$ to demonstrate the process of finding these values using calculus. In this article, we will answer some frequently asked questions related to finding absolute maximum and minimum values of a quadratic function.

Q: What is the difference between absolute maximum and absolute minimum values?

A: The absolute maximum value of a function on a given interval is the largest value that the function attains on that interval. Similarly, the absolute minimum value is the smallest value that the function attains on that interval.

Q: How do I find the critical points of a function?

A: To find the critical points of a function, you need to set the derivative of the function equal to zero and solve for $x$ . You can also use the power rule of differentiation to find the derivative of the function.

Q: What is the power rule of differentiation?

A: The power rule of differentiation states that if $f(x) = x^n$ , then $f'(x) = nx^{n-1}$ .

Q: How do I evaluate the function at the critical points and the endpoints?

A: To evaluate the function at the critical points and the endpoints, you need to substitute the values of $x$ into the function and simplify.

Q: What is the significance of the absolute maximum and minimum values?

A: The absolute maximum and minimum values of a function are important because they help us understand the behavior of the function on a given interval. They can also be used to determine the maximum and minimum values of the function.

Q: Can I use calculus to find the absolute maximum and minimum values of a function on an interval?

A: Yes, you can use calculus to find the absolute maximum and minimum values of a function on an interval. This involves finding the critical points, evaluating the function at these points and the endpoints, and comparing the values to find the absolute maximum and minimum values.

Q: What are some common mistakes to avoid when finding absolute maximum and minimum values?

A: Some common mistakes to avoid when finding absolute maximum and minimum values include:

Not setting the derivative equal to zero to find the critical points
Not evaluating the function at the critical points and the endpoints
Not comparing the values to find the absolute maximum and minimum values
Not considering the endpoints of the interval

In this article, we have answered some frequently asked questions related to finding absolute maximum and minimum values of a quadratic function. We have also provided some tips and common mistakes to avoid when finding these values. By following these tips and avoiding these mistakes, you can ensure that you find the absolute maximum and minimum values of a function on a given interval.

If you are interested in learning more about finding absolute maximum and minimum values of a quadratic function, we recommend the following resources:

Calculus textbooks and online resources
Online tutorials and videos
Practice problems and exercises

By using these resources, you can gain a deeper understanding of the concept of absolute maximum and minimum values and how to find them using calculus.