# Integration of Function of Two Variables

1. Sep 29, 2010

### PeterFer

1. The problem statement, all variables and given/known data

For one of my physics classes I need to integrate a function of two variables, but I haven't learned how to do it yet in my calculus classes. If anyone could explain to me how to do it, it would be much appreciated. It's probably pretty simple I just haven't learned it yet.

the integral is $$\int$$ (z 2 + x2)-3/2 dx

and i know that the answer is x/ sqrt (z2 + x2) z2

thanks

2. Sep 29, 2010

### Char. Limit

z^2 is a constant with respect to x. That might help.

3. Sep 29, 2010

### PeterFer

yea I've been trying to think of it that way but everything i do doesn't end up working and I can't think of anything else to do

4. Sep 29, 2010

### ╔(σ_σ)╝

You can make a trig substitution.

5. Sep 29, 2010

### PeterFer

I think I understand where the sqrt(z2 + x2) in the denominator of the answer comes from, if you pretend z2 + x2 is one term and take its anti-derivative you get 1/sqrt(z2 + x2), but i dont know where the x in the numerator or the z2 in the denominator come from

6. Sep 29, 2010

### ╔(σ_σ)╝

What happens if you make x= ztan$$\theta$$.

7. Sep 29, 2010

### PeterFer

oh wow thank you so much, I completely forgot about trig substitution. Thanks a lot I just got it