Integration of a square root inside another square root function. Integrate the following $$\int_0^5 \sqrt{5-\sqrt{x}} \ \mathrm{d}x$$ I have done the following: 
I got the expression under the square root to equal $$5-x^{1/2}$$ so the integral then becomes $$\int_0^5 \left(5-x^{1/2}\right)^{1/2}\ \mathrm{d}x$$ Here is where I am stuck. Do I need to use some variation of the binomial theorem here?
I hope my use of MathJax was "up-to-code" here. I apologize if not.

Hint: The substitution $u=5-\sqrt x$, i.e. $x=(5-u)^2$ yields 
$$
\int \sqrt u (-2(5-u))\,du
$$
for some new limits that I'm not going to compute right now.
