# relative extrema question

• Dec 4th 2009, 12:37 PM
dangerous1
relative extrema question
f(x) = x^4 + 4/3 x^ 3 - 4x^2
find and identify the relative extrema of f by applying the second derivative test.

i got relative max at (-2, -10.6) and (1,-1.6)

i got relative min at (0,0)
am i right
• Dec 4th 2009, 12:42 PM
mr fantastic
Quote:

Originally Posted by dangerous1
f(x) = x^4 + 4/3 x^ 3 - 4x^2
find and identify the relative extrema of f by applying the second derivative test.

i got relative max at (-2, -10.6) and (1,-1.6)

i got relative min at (0,0)
am i right

- Wolfram|Alpha shows that your values of x are correct. I assume you can correctly calculate the double derivative of a quartic and substitute these values of x into it to determine their nature. And I assume you can correctly substitute these values into the equation for y to get the y-coordinates.

If you want answers checked you will need to post all of your work. (I help students when they're stuck, I don't check answers when the student clearly knows what to do).