yeah, there is a fundamental thing, which is that the mutually exclusive conditions f(x) < g(x), f(x) = g(x), f(x) > g(x) always divide the real line into disjoint regions, and under normal highschool type circumstances the set f(x) = g(x) is a set of "points," and the other sets are intervals separated by those points, and you can use information about any one of these sets to sort of guess at the structure of the others.