Hey can you guys help me out with this problem:

It is given that $\displaystyle \frac{a}{b+\sqrt{c}} + \frac{d}{\sqrt{c}}$ is rational, where a,b,c and d are positive integers and c is not a square. Show that as a consequence, $\displaystyle db^2 = c(a+d)$. Use this result to show that $\displaystyle \frac{a}{1+\sqrt{c}} + \frac{d}{\sqrt{c}}$ is not rational.

Thanks!