Note how the graph goes on forever in both left and right directions. So x extends forever in both directions. This means any x can be an input to the function. The domain is -infinity < x < infinity. Basically, the domain is the set of all real numbers.
The range is -infinity < y <= 9000 since there is no smallest y value, but the largest y can be is y = 9000. Look at the highest point of the parabola and note the y coordinate of this point. This highest point is called the vertex.
