Closed Formula for Geometric Series and Sums

I just have two questions regarding closed form formulas for geometric series and summing infinite series.

For the closed form formula, I have an expression for the $\displaystyle nth$ term:

$\displaystyle 7(7/8)^n$

But I am not sure how to convert this to closed form since I am not really sure what closed form looks like. Is it just to convert it into a finite sum equation like this:

$\displaystyle

\frac{7(1-\frac {7} {8}^n)} {(1- \frac {7} {8})}$

For the infinite series, I have the formula:

$\displaystyle \frac {1} {4} \sqrt{h}$

Where $\displaystyle h = 7(7/8)^n$

So the very first term would be:

$\displaystyle \frac {1} {4} \sqrt{7\frac {7} {8}}$

And this would go in the numerator, but I am not sure what would go in the denominator. I really appreciate everyone's help.