f(x)=2x^2-2x-12

Question

domain of function using set builder notation

Answer 1

All real numbers (actually, all complex numbers!)  OR:

- ∞ < x < ∞     OR

x ∈ (-∞,∞)       OR

{ x | x ∈ (-∞,∞) }

 

In case of complex numbers:  Let  x = u + iv,  and i = √-1,  then and   u ∈ (-∞,∞)  and  v ∈ (-∞,∞) ; etc, etc...  :-)