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# Partials Diff and Stationary Points watch

1. Hello!

I've been given a question in which I need to find the local extreme points of the equation .

I've done the usual of calculating .

Now the problem comes with how can I tell which x coordinate corresponds with which y coordinate?
Wolfram tells me that the extreme points are (0,0) and (8,6) - but how do I know that I shouldn't be looking at (0,6) and (8,0)?

Thanks!
2. If you're not sure find the second derivative of both and try work from there.
3. (Original post by RPowell95)
Now the problem comes with how can I tell which x coordinate corresponds with which y coordinate?
Wolfram tells me that the extreme points are (0,0) and (8,6) - but how do I know that I shouldn't be looking at (0,6) and (8,0)?
All four points satisfy your first derivative equations (each x goes with each y), and you need to check all four to determine which are the local extrema.

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Updated: October 28, 2015
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