Question

How do I find the domain for f(x)=2x^2+2?

Answer 1

Domain is all permissible input for which the output exists/defined.

Can you think of any value of x for which f(x) is not defined?

Answer 2

You just look at it. \(\mathbb{R}\)

Generally, you start with all real numbers and think about what does not work and throw it out if you find something. You will never find something with a polynomial.