Hi all,

I'm going through a application for learning maths and I've hit a confusing point, unfortunately it fails to depart with any information on workings out of a problem.

The app informs me that:

$\displaystyle x = \frac{4 \pm \sqrt{20}}{2}}$

Reduces to this:

$\displaystyle x = {2 \pm \sqrt{5}}$

I have no idea how that radical is being divide by the whole number, basically I need to know how I would make this:

$\displaystyle \frac{\sqrt{20}}{2}}$

Reduce to this:

$\displaystyle \sqrt{5}$

Thanks in advance.