1. The square-root function and the ln-function are both continuous and differentiable in their respective domains. So determine the domains of these partial functions and afterwards determine the domain of f.

2. The square-root function is continuous and differentiable if

..........[A]

3. The ln-function is continuous and differentiable if

..........["B"]

4. The denominator of the fraction must be unequal to zero: ..........[C]

That means: x = 1 doesn't belong to the domain of f.

5. Now "construct" a valid domain and write it in interval form.