Why $\frac{x}{\sqrt{x+1}-1}$ can be written as $\sqrt{x+1}+1$? I've evaluated the first formula on $W|A$ and it says that $\sqrt{x+1}+1$ is an alternate form to the first expression. I just don't see how it's possible. 
The first thing I imagined was to write:
$$\frac{x}{\sqrt{x+1}-1}=x^1(\sqrt{x+1}-1)^{-1}$$
But it doesn't seems to give me much insight.

Multiply Numerator and denominator by $sqrt(x+1) + 1 $ and see ...
