Math Is Fun Forum

dexza666

Member

Registered: 2008-04-21

Posts: 5

chain rule

Let f = f(u,v) and u = x + y, v = x - y

i) assume f to be twice differentiable and compute f_{xx} and f_{yy} in terms of f_{u}, f_{v}, f_{uu}, f_{uv} and f_{vv}.

ii)express the wave equation:

((∂²f)/(∂x²))-((∂²f)/(∂y²))=0

in terms of partial derivatives of f with respect to u and v.

luca-deltodesco

Member

Registered: 2006-05-05

Posts: 1,470

Re: chain rule

assuming i did all that right:

Last edited by luca-deltodesco (2008-04-22 17:54:53)

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luca-deltodesco

Member

Registered: 2006-05-05

Posts: 1,470

Re: chain rule

Perhaps a bit of tangent, but i want to test whether i got it right or not with an example.

So it does seem i was correct in my answers for you

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The Beginning Of All Things To End.
The End Of All Things To Come.