It turns out all we need to know in order to determine the range of a quadratic function is the -value of the vertex of its graph, and whether it opens up or down. This is easy to tell from a
Constantly using it for home work to understand where I miscalculated. You even have an option to go premium, for the step by step solutions, or you could go watch an ad for the step by step solutions, have never seen a better calculator, though, it is a bit slow, so maybe try optimising it, other then that, I have no issues.