Single variable calculus question. (first post)

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Discussion Overview

The discussion centers around the first derivative test for finding relative extrema in single variable calculus. Participants explore the conditions under which local maximums and minimums occur, as well as the interpretation of the derivative in relation to the graph of a function.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Homework-related

Main Points Raised

  • One participant asks for clarification on how to perform a first derivative test to identify relative extrema.
  • Another participant explains that local maximums and minimums occur at points where the derivative is zero or does not exist, emphasizing the importance of checking endpoints as well.
  • A different participant introduces the concept of horizontal inflection points, noting that they also occur at points where the derivative is zero, using the example of the function y=x³ at x=0.
  • Further contributions include a visual representation of the function and its derivative, discussing the significance of the gradient and the conditions for identifying maxima and minima.

Areas of Agreement / Disagreement

Participants generally agree on the basic principles of the first derivative test, but there are nuances regarding the interpretation of points where the derivative is zero, particularly concerning horizontal inflection points.

Contextual Notes

The discussion includes assumptions about the continuity and differentiability of functions, as well as the specific conditions under which the first derivative test applies. There may be unresolved mathematical steps related to the graphical representation of the function.

Who May Find This Useful

Students and individuals seeking clarification on the first derivative test in calculus, particularly those looking for conceptual understanding and graphical interpretations.

physicsstudent04
Hi I'm new to this forum.
I was wondering if anyone can explain to me how to do a first derivative test to find the relative extrema. I've been trying to read it, but it just isn't sinking in. thanks in advanced.
 
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If a function is continuous and differentiable then local maximums amd minimums occur where the graph of a function is flat, so they occur where the derivative is zero.

So, when looking for maximums and minimums you only need to check endpoints, and points where the derivative is zero or doesn't exist.
 
There is third possibility for zero derivative points, horizontal inflection point. Example y=x3, at x=0.
 
thanks a lot guys. appreciate the help.
 
please open the attachment below, to get better picture...
(note : that the picture is the graph f(x) against x )

actually to see the better idea of first derivative by imagining it as a gradient of the graph of a fuction.

suppose I have fuction f(x)

when you derive it becomes f'(x)...
what is f'(x) ?

f'(x) is the gradient...

now look at the picture that there are 3 red straight lines.you can get line straight ,if and only if at the turning point like what you see in the graph

at the other point you will find the line is slope like both the blue line.

remember that straight line has gradient 0...that is to say, f'(x)=0

so to find either maxima or minima ,you must find value of x ,which can be subtituted into f'(x) and get value 0.
 

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