So I am trying to follow an example in my text which and I found a step that I cannot follow. The example is showing convergence or divergence using an alternating series test lim(n-> inf).

The original problem is:

$\displaystyle (sum)[n=1] ( (-1)^(n+1) n^2 ) / (n^5 +5)^(1/2)$

The step I do not understand is from:

$\displaystyle n^2 / (n^5 +5)^(1/2)$

To:

$\displaystyle 1 / (n + 5/(n^4) )^(1/2)$

I don't understand how it was simplified through the radical. Can anyone help me?