2 Differential Calculus of Functions of one Variable

The derivative measures instantaneous rate of change, and this section develops it from the limit concept on which it rests.

The order is deliberate. Limits come first, since the derivative is defined as one, together with the techniques for evaluating them and the indeterminate forms where naive substitution fails. Continuity follows, being defined by a limit condition. The mean value theorems come next: they look modest but are the bridge from local information — the derivative at a point — to global conclusions about a function on an interval, and almost every later result depends on them.

The section then turns to infinite series, where the question is when adding infinitely many terms produces a finite answer, and to the representation of functions as power series. It closes with curvature, which applies the derivative to measure how sharply a curve bends and prepares the ground for the treatment of space curves in the section on vectors.

Questions on this section

Stuck on something here? Ask below and it stays attached to this topic.