This observation verifies what we already know mathematically; namely the fact that f(x) = 3x + 1 tells us that every time x increases by 1 unit, f(x) increases by 3 units. Note next In our geometric graph, this is shown in the equivalent form that when x increases by 2, y increases by 6.
In other words, when we decide that a finite number of points is enough to determine the curve that passes through them, we are using inductive reasoning. That is, we analyze what we think these points have in common. However, we can never be sure that what we surmised is factually true. Note next