Quick math question!
How do I evaluate (d^2)/(dxdy)?
Is it just d/dx*d/dy? Thanks! 
hi btbam91! :smile:
Quote:
(and it's also ∂/∂y*∂/∂x) 
Re: Quick math question!
Hmmm, double check my work because I must be doing something wrong!
I'm looking to evaluate (d^2)/(dxdy) of F, where F = ax^2+bxy+cy^2 So for dF/dx, I get 2ax+by. For dF/dy, I get bx+2cy. So, multiplying both together and accounting for the negative sign: [(2ax+by)*(bx+2cy)]= [2abx^2+4acxy+b^2xy+2bcy^2] The answer is supposed to be b according to the solution manual (that doesn't show the solution :p) Am I missing something here? Thanks! 
Re: Quick math question!
Do not multiply, but apply each differential sequentially. So after finding the first differential, do the second on the resulting expression. Order is not critical.

ohhh! :smile:
i assumed you meant ∂/∂x of ∂/∂y … you ∂/∂y it first, then you ∂/∂x it … ∂(∂F/∂y)/∂x :wink: 
Re: Quick math question!
Oh! I got it now! Thanks fellas!

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