Find all intervals for which the graph of the function y=(8x^3) - (2x^4) is concave downward.
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Concavity is test with the second derivative test.
What is the 2nd derivative of y?
The first is
Once you have the second derivative, set to obtain the inflection points. Spoiler:
What does this tell you now?
Last edited by dwsmith; December 17th 2010 at 07:41 PM.
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