Find the domain of the function. Write in interval notation.

sqrt(x^2 − 64).

For the answer, I got (-infinity, -8)u(8, infinity), but that's wrong, and I'm not sure what else to try?

1 answer

if you allow taking imaginary roots, then the domain is -inf to +inf.

If you allow only real roots, then must be less than -8 or greater than 8, your answer.

consider x=3
sqrt(9-64)=sqrt(-55)=i*sqrt55