Set the denominator equal to zero. Remember, dividing by 0 is undefined. So if we find values of x that make the denominator zero, then we must exclude them from the domain.
Subtract 4 from both sides
Take the square root of both sides
Since you cannot take the square root of a negative number and get a real number, the result will be imaginary
So that means there are no real numbers which will make the denominator equal to zero