Mathnoob wrote at 2010-10-12 02:42:57
Part C is actually a local maximum because when the second derivative is less than 0, it is concave down, making it a upside down U because concaved up is when the derivative is bigger than 0, and it is a U shape which results in a local minimum.

ben wrote at 2011-11-09 17:12:43
The previous answer is incorrect, because if the second derivative is negative, then the curve is concave down, and this the curve has a local maximum art the given point.

anon. wrote at 2012-05-20 22:27:20
it is actually a local maximum, because the second derivative is negative, which means it is concave down, which implies that it reaches a maximum value.

J wrote at 2014-11-04 02:56:50
Just on part c. It would actually be a local maximum. d^2y/dx^2 is negative which means the original curve is concave down which means there is a maximum at (3,2). Also (3,1/4) is another valid point on the original curve which means (3,2) can't be a minimum

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