# Order of PDE

1. Nov 14, 2009

### saravanan13

what is the order of differential equation which contains first order in time and second order in space derivative?

2. Nov 14, 2009

### elibj123

it will be the order of the highest derivative (doesn't matter in respect to what variable).
In your case, it's a second order pde

3. Nov 14, 2009

### HallsofIvy

Although it would also be perfectly acceptable to say "The differential equation is of second order in x and first order in t".

4. Nov 15, 2009

### elibj123

It is a more specific classification

But in respect to how you solve the PDE, it's only important what's the highest order.

In this matter, how would you classify $$u_{xt}+blabla=0$$, first order in time and space, or second-order in both?

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