The height of a football y in feet is given by the function y=-16x^2 +56x+2 where X is the time in seconds after the ball was kicked calculate how long the football was in the air

The domain of a function can be represented by which one of the following options? o a. a set of output values o b. a set of f(x) values o c. a set of input values o d. a set of both input and output values