evaluate the triple integral $z/( x^2 + z^2)$ 
i set this up in the order $dxdzdy$ and i tried factoring out the z, but I'm not sure how to integrate the denominator. I tried raising it to the -1 power and putting it to the top, and using u substitution, but there is no extra x. Can someone show me detailed steps on how to do this triple integral?

Your innermost integral is with respect to $x$, and after factoring our the $z$ from the numerator, you need to integrate $\displaystyle\int_0^z\frac{1}{x^2+z^2}\,dx$ (for this innermost integral). Hint: there are two useful antiderivative rules for functions like this:
$$\int\frac{1}{1+x^2}\,dx=\arctan(x)+C \quad \text{and} \quad \int\frac{1}{a^2+x^2}\,dx=\frac{1}{a}\arctan\left(\frac{x}{a}\right)+C,$$
where in the second one we assume $a>0$.
