Start with the given function g(x)=1√x2+2x+6 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. √x2+2x+6=0
⇒x2+2x+6=0
If we find the roots of the above quadratic equation we get the imaginary values for x. The domain is: (−∞,+∞).