List of top Quantitative Aptitude Questions on Progression asked in CAT

If a1,a2,..... are in A.P., then, \(\frac{1}{\sqrt{a_1} + \sqrt{a_2}} + \frac{1}{\sqrt{a_2} + \sqrt{a_3}} + .... + \frac{1}{\sqrt{a_n} + \sqrt{a_{n+1}}}\) is equal to