1. All your functions depend on the variable x even though x isn't "visible". But for instance

is the same as and here you have your x.

2. You have to prove for each function if there exist any constraints of x such that the term f(x) can't be calculated.

The constraints you are supposed to know are:

i) The denominator of a fraction must unequal zero.

ii) The radical of a square-root must be non-negative.

iii) The argument of a logarithm-function must be positive.

3. There is only one function in your list whose domain isn't