# Increasing/Decreasing, Concave Up/Down, Inflection Points | Summary and Q&A

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October 31, 2015
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blackpenredpen
Increasing/Decreasing, Concave Up/Down, Inflection Points

## TL;DR

Analyzing the function f(x) = 2x^3 + 3x^2 - 36x to determine intervals of increasing, decreasing, concavity, and find local maximum and minimum values.

## Key Insights

• ❓ The first derivative of a function can be used to determine the intervals of increasing or decreasing.
• 🤘 The sign of the second derivative helps identify the intervals of concavity.
• 😥 Critical numbers and points of inflection play a crucial role in finding local maximum and minimum values.
• 💠 Analyzing the behavior of the first derivative and second derivative can provide insight into the overall shape of a function.
• ❓ Understanding calculus concepts like increasing, decreasing, concavity, and local extremas is essential in optimizing and analyzing functions.
• 😥 The process of finding critical numbers, points of inflection, and local extremas involves solving equations and utilizing the properties of derivatives.
• 📈 Graphing the function can assist in visualizing the function's behavior and confirming the analysis.

## Transcript

for this question we're keeping the function f of X equal to 2x to the third power plus 3x squared minus 36 x first we have to find out the intervals which f is increasing or decreasing and to do that we need our first derivative so let's go ahead and do our first derivative F prime X that the rooty of 2x plus third power will be 6x squared and eit... Read More

### Q: How do you find the intervals where the function f(x) is increasing or decreasing?

To find the intervals of increasing and decreasing, you need to find the critical numbers of the function by setting the first derivative equal to zero. Then, you can use the first derivative test to determine the sign of the first derivative and identify the intervals.

### Q: How do you determine the concavity of the function?

To determine the concavity of the function, you need to find the second derivative and set it equal to zero to find the points of inflection. Then, you can use the second derivative test, plugging values from the intervals into the second derivative expression to determine the sign of the second derivative and identify the intervals of concavity.

### Q: How do you find the local maximum and minimum values of the function?

To find the local maximum and minimum values of the function, you need to identify the critical numbers and use them to locate the points where the first derivative changes sign. Then, you can plug these values into the original function to find the corresponding y-values and determine the local maximum and minimum values.

### Q: What are the intervals in which the function is increasing, decreasing, concave up, and concave down?

The function is increasing in the intervals (-∞, -3) and (2, ∞), decreasing in the interval (-3, 2), concave up in the interval (-1/2, ∞), and concave down in the interval (-∞, -1/2).

## Summary & Key Takeaways

• The content explains how to find the intervals where the function f(x) is increasing or decreasing by finding the critical numbers and using the first derivative test.

• It demonstrates how to identify the concavity of the function by using the second derivative test and locate points of inflection.

• The video also shows how to find the local maximum and minimum values of the function by analyzing the behavior of the first derivative.