]> Note

Note

The way mathematicians like to express this statement is as follows: "For every epsilon greater than zero there is a delta such that for | x x ' | < delta and x ' x the difference between f ( x ) f ( x ' ) x x ' and the slope of that line is less than epsilon".
This has a tendency to confuse beginners who are put off by the symbols for delta and epsilon as much as they are by the concepts. However it grows on you, apparently.