|Nov8-05, 10:28 AM||#1|
I'm trying to complete the question below:
Find the 2 stationary points of F and show that one of them is a minimum of F.
I've got as far as getting:
dF/dx = 2/3x+2y+2
dF/dy = 2x+2y+2
I would like to know what i need to do next (do i have to treat the above two terms as simultaneous equations?)
Any help will be appreciated
|Nov8-05, 10:39 AM||#2|
Be careful, if your initial function F(x,y) is correct then you've got a wrong partial derivative with respect to x. I see a x³/3 and its derivative should give x² and I don't see that term in your dF/dx. dF/dy seems to be correct.
Once you have the right partial derivatives, let them equal zero and solve them together (system of 2 equations). This gives the stationary points.
|Nov8-05, 12:52 PM||#3|
Thanks for your reply,
You're correct, it should read:
dF/dx = 2/3x^2+2y+2, which i wrote down in my notes!Typo error.
When you say, solve them together, do you mean like you do with simultaneous equations?
I tried that route but i'm getting confused with what to do with the term that's a fraction.
so i assume that the 2 term cancels,as does the 2y and then i get lost.
|Nov8-05, 12:54 PM||#4|
Yes, a system of equations so simultaneous equations.
By the way, (x³/3)' = x² and not 2x²/3...
Be careful with your derivatives, else the stationary points will be wrong too of course!
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