# How to find the implied domain of a function

Learn how to find the domain of rational functions with a radical numerator. Recall that the domain of a function is the set of possible input values (x-values) of the function. For a rational function, the denominator cannot be zero and for radical functions, the value inside the radical cannot be negative. Thus, to find the domain of a rational function with a radical numerator, we set up the value inside the radical as an inequality greater than or equal to 0 and solve the inequality for the variable. We also set up the denominator equal to zero and solve for the variable. The set of values satisfying the inequality except for the value of the variable for which the denominator is zero is the required domain.