partial derivatives

[dcm18]

I was hoping someone can help me out here......

 

What is the Partial Derivative for the following fuctions:

 

d^2/dx^2 (e^(-i (3x+2y)) )

 

d/dx √(x^2+y2)

 

 

Any guidance would be much appreciated!

 

Thanks

[PhDP]

Where are you getting stuck ?

 

It shouldn't be too hard to solve if you remember the basic rules;

 

[math]

\frac{d}{dx} f(x)^a = af(x)^{a-1}\times \frac{df(x)}{dx}

[/math]

 

[math]

\frac{d}{dx} e^{f(x)} = e^{f(x)} \times \frac{df(x)}{dx}

[/math]

 

[math]

\frac{d}{dx} f(y) = 0

[/math]

[Country Boy]

Notice that Phil has written that entirely in terms of ORDINARY derivatives.

 

That's perfectly correct- you just have to remember that since all of the partial derivatives are with respect to x, that "y" is just a constant.

[dcm18]

OH ok ......Thanks a lot guys that was a big help