Finding the point of inflection for the function

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Homework Help Overview

The discussion revolves around finding points of inflection for the function y = x - cos x on the interval {0, 2pi}. Participants are exploring the implications of the second derivative, which is identified as cos x, and its behavior at specific points.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants discuss the identification of points where the second derivative equals zero and question whether these points represent inflection points. There is also inquiry into how to verify changes in concavity around these points.

Discussion Status

Some participants have provided guidance on checking for changes in concavity around the identified points of pi/2 and 3pi/2, suggesting specific numerical values to test. However, there is still uncertainty regarding the final answer and the method of verification.

Contextual Notes

Participants are working within the constraints of a homework assignment, focusing on the interval {0, 2pi} and the requirement to determine points of inflection without providing complete solutions.

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Homework Statement



Find any points of inflection for the function y = x - cos x on the interval {0,2pi}

Homework Equations





The Attempt at a Solution



Well i know the second derivative is cos x, and I know it equals 0. But I am just not sure what to give as a final answer. cos x = 0 at pi/2 and 3pi/2 but is that the final answer?

Thank you for your help!
 
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meeklobraca said:

Homework Statement



Find any points of inflection for the function y = x - cos x on the interval {0,2pi}

Homework Equations





The Attempt at a Solution



Well i know the second derivative is cos x, and I know it equals 0. But I am just not sure what to give as a final answer. cos x = 0 at pi/2 and 3pi/2 but is that the final answer?

Thank you for your help!
cos(x) is not identically zero. To confirm that there are inflection points for x = pi/2 and x = 3pi/2, check to see whether the concavity changes around these values. IOW, does y'' change sign at pi/2 and 3pi/2? If so, you're almost done, and the only other thing is to find the y values at these points. Those will be your inflection points.
 
how do I check around those values, I am not sure how to use something like pi/2 in this case.
 
Then use pi/2+ .001 and pi/ - .001! What do you mean "use pi/2"? It is a number! enter it into your calculator. Be sure you calculator is set to "radian" mode of course.
 

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