Finding the point of inflection for the function

In summary, to find any points of inflection for the function y = x - cos x on the interval {0, 2pi}, you can use the second derivative test to check for changes in concavity. The second derivative, cos x, equals 0 at x = pi/2 and x = 3pi/2, but to confirm these points as inflection points, you must check if the concavity changes around these values. You can do this by using values slightly greater and less than pi/2 and 3pi/2, such as pi/2 + .001 and pi/2 - .001. Once you have confirmed the points, you can find the y values at these points to determine the inf
  • #1
meeklobraca
189
0

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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  • #2
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.
 
  • #3
how do I check around those values, I am not sure how to use something like pi/2 in this case.
 
  • #4
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.
 

1. What is the point of inflection for a function?

The point of inflection for a function is the point where the concavity of the function changes. It is the point where the function transitions from being concave up to concave down or vice versa.

2. How do you find the point of inflection for a function?

To find the point of inflection for a function, you must first find the second derivative of the function. Then, set the second derivative equal to zero and solve for the variable. The resulting value will be the x-coordinate of the point of inflection.

3. Can a function have more than one point of inflection?

Yes, a function can have multiple points of inflection. This occurs when the concavity of the function changes multiple times within the domain.

4. What does the point of inflection tell us about a function?

The point of inflection can tell us about the behavior of the function. It marks the transition from increasing to decreasing or vice versa and can also indicate the presence of local maximum or minimum points.

5. Is there a graphical way to find the point of inflection for a function?

Yes, the point of inflection can also be found graphically by observing the shape of the graph. The point of inflection will be the point where the curve of the graph changes from concave up to concave down or vice versa.

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