Max points, points of inflection

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SUMMARY

The discussion centers on finding the maximum and minimum points, as well as the inflection points, for the function y=4x^3 - 3x^4. The participant initially identifies two local maximum points but is corrected by others who clarify that there is only one maximum point. The confusion arises from the need to verify that critical points are indeed local extrema. The second derivative test reveals two inflection points at x=0 and x=1/2, although there is disagreement regarding the accuracy of this result.

PREREQUISITES
  • Understanding of calculus concepts such as derivatives and critical points.
  • Familiarity with the second derivative test for concavity and inflection points.
  • Knowledge of polynomial functions and their behavior.
  • Ability to differentiate functions and solve equations.
NEXT STEPS
  • Review the definitions of local extrema and inflection points in calculus.
  • Practice using the second derivative test on various polynomial functions.
  • Explore the implications of critical points in determining function behavior.
  • Learn how to graph polynomial functions to visually identify max/min and inflection points.
USEFUL FOR

Students studying calculus, particularly those focusing on polynomial functions and their properties, as well as educators seeking to clarify concepts of maxima, minima, and inflection points.

fitz_calc
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Homework Statement



which best describes y=4x^3 - 3x^4
find max/min points and inflection points

The Attempt at a Solution



When I work this one out I get x<0 and 0<x<1 as my two local max points. However, the book says there is only ONE max point - why is this?

with the second derivative I do get two inflection points of 0 and 1/2 which I assume to be correct.

Thoughts??
 
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I think that you'll see where your mistakes are once you write down a clear definition of an inflection point, and of a local extremum. I'll go ahead and say this (because it's often a step that students forget): did you check that your critical points are in fact local max/min points? Likewise for inflection points.

Can you also post your solution?
 
fitz_calc said:

Homework Statement



which best describes y=4x^3 - 3x^4
find max/min points and inflection points

The Attempt at a Solution



When I work this one out I get x<0 and 0<x<1 as my two local max points. However, the book says there is only ONE max point - why is this?
That makes no sense at all. Max/min points are individual points, not sets of points. HOW did you "work this one out"? If you mean that you got x= 0 and x= 1 as your max/min points, it is true that the derivative is 0 at x= 0 and x= 1, but that is not enough to be a max or a min.

with the second derivative I do get two inflection points of 0 and 1/2 which I assume to be correct.
That is not at all what I get. What is the second derivative?
 

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