I will take the positive square root since surface area must be positive. Therefore, the integrand can be simplified to:
Thus the integral becomes:
Apply a substitution...primarily . Thus . Solving for , we get .
Before we substitute, we can change the limits of integration as well. The upper limit will become and the lower limit will become .
Now, the integral can be rewritten as:
evaluating the integral we get:
Hope that helped you out!