calculus - The integral problem: $int_{0}^{16}frac{dx}{sqrt{x^2+9}-sqrt{x}}$

I have met this kind of problem today.in fact, I spent hours trying to solve this problem on its own. My method was just to calculate the indefinite integral. I looked at Wolfram Alpha after I failed. Wolfram couldn't evaluate this integral. I don't know the spesific reason.

The integral:

$$\int_{0}^{16}\frac{dx}{\sqrt{x^2+9}-\sqrt{x}}$$