# Homework Help: Partial differential eqn

1. Nov 5, 2009

### jenuine

Consider the partial differential equation 2dz/dx-dz/dy=0
Show that if f(u) is a differential function of one variable, then the partial differential equation is satisfied by z=f(x+2y)

3. The attempt at a solution: Change of variables?????? No idea :S

2. Nov 5, 2009

### HallsofIvy

Here's a suggestion: DO WHAT IT SAYS! If z= f(x+ 2y), what is $\partial f/\partial x$? What is $\partial f/\partial y$? Let u= x+2y and use the chain rule.

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