Partial Derivatives: Help & Thanks!

imana41
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please help about this
if f(u,v)=f(y/x,z/x)=0 and z=g(x,y) and
gif.latex?\frac{\partial%20f}{\partial%20v}\neq%200.gif


show
gif.latex?x\frac{\partial%20g}{\partial%20x}+y\frac{\partial%20g}{\partial%20y}=g(x,y).gif


thanks alot
 
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imana41 said:
please help about this
if f(u,v)=f(y/x,z/x)=0 and z=g(x,y) and
gif.latex?\frac{\partial%20f}{\partial%20v}\neq%200.gif


show
gif.latex?x\frac{\partial%20g}{\partial%20x}+y\frac{\partial%20g}{\partial%20y}=g(x,y).gif


thanks alot

Can you calculate df/dx and df/dy?
And do you know which value they would take?
 
df/dx = df/du . du/dx + df/dv .dv/dx and lik this for df/dy
 
imana41 said:
df/dx = df/du . du/dx + df/dv .dv/dx and lik this for df/dy

True.

And since f(y/x, z/x) = 0 it follows that df/dx=0 and that df/dy=0.

So if you write out the equations for df/dx and df/dy you have 2 equations that can be solved.
 
20u}{\partial%20y}+\frac{\partial%20f}{\partial%20v}\times%20\frac{\partial%20v}{\partial%20y}=0.gif


but how i linking it to
gif.gif
 
imana41 said:
20u}{\partial%20y}+\frac{\partial%20f}{\partial%20v}\times%20\frac{\partial%20v}{\partial%20y}=0.gif


but how i linking it to
gif.gif

You are forgetting to substitute u=y/x and v=g(x,y)/x
 
thanks i get the answer
the latest symplify is
\frac{\partial%20g}{\partial%20x}\times%20x-g(x,y)}{x\times%20\frac{\partial%20g}{\partial%20y}}.gif


and then
gif.latex?x\frac{\partial%20g}{\partial%20x}+y\frac{\partial%20g}{\partial%20y}=g(x,y).gif
thanks for your help
and another answer is it true
gif.gif
 
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