ABOUT ONE TOPIC FOR MATHEMATICAL CIRCLES - DERIVATIVE FUNCTION (COUNTEREXAMPLES)

10.09.2022 International Scientific Journal "Science and Innovation". Series A. Volume 1 Issue 5

A. Raximov , Y. Tillaboev

Abstract. The article provides a brief overview of the origin of the derivative, also discusses the issues that students face in lectures on mathematical analysis in universities. A list of questions has been compiled and systematized that the teacher should pay special attention to in mathematical circles. In particular, examples are given of several functions (from the Internet) that are continuous in the interval but do not have a derivative. The functions constructed by the leading mathematicians Bolzano B., Weierstrass K. and Van der Waerden are analyzed in detail. The Van der Waerden function is analyzed in more detail. The main purpose of writing the article is to systematize the available information about continuous but non-differentiable functions and give recommendations for their explanation in circles.

Keywords: mathematical analysis, derivative, interval, continuity, periodicity, broken line, sequence.