All real numbers or (negative infinity, positive infinity)
Step-by-step explanation:
The equation given is a parabola. A parabola has infinite values of x inputs that produce an infinite amount of y outputs. All values of x produce an output, so any number of x would work.
(-∞,+∞), since any quadratic equation graph (quadratic parabola) has only range restrictions (the min and max), but the for any x value there is a y value.
