# C2-solutions to a diff.equation.

1. Dec 14, 2014

### Hatmpatn

I have the following problem:
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Calculate all the C2-solutions z(x,y) to the differential equation:

with the following constraint:
by making the substitution u=xy, v=x

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Solution
I've begun slightly but this doesn't take me far..

2. Dec 14, 2014

### pasmith

Start by working out what the differential operators $\frac{\partial}{\partial x}$ and $\frac{\partial}{\partial y}$ are in terms of $u$, $v$ and the differential operators $\frac{\partial}{\partial u}$ and $\frac{\partial}{\partial v}$. From these you can find expressions for the second-order operators.

Now substitute these expressions into the original PDE, and tidy up the result. You should find that most of the terms cancel.

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