# calculus question help

• Oct 14th 2008, 08:34 PM
rachellediamond130
calculus question help
can someone help me with this question????/

http://farm4.static.flickr.com/3002/...e2d4bf.jpg?v=0
• Oct 14th 2008, 08:49 PM
natashabu
Well since it's the graph of f', f is decreasing when f' is negative. f' is negative when it's below the x-axis.

and a local maximum is when f' is positive, then 0 (horizontal tangent), then negative..

local minimum when f' is going from negative, 0, and then positive again.
• Oct 14th 2008, 08:52 PM
mr fantastic
Quote:

Originally Posted by rachellediamond130
can someone help me with this question????/

http://farm4.static.flickr.com/3002/...e2d4bf.jpg?v=0

Here is what you need to know and use:

f is increasing when f' > 0.

f is decreasing when f' < 0.

Stationary point when f' = 0. Nature of stationary point. Use sign test:

Let a < b < c.

Local max at x = b if f'(b) = 0 and f'(a) > 0 and f'(c) < 0.

Local min at x = b if f'(b) = 0 and f'(a) < 0 and f'(c) > 0.