SUMMARY
The discussion focuses on proving the continuity of the function defined as $$f(x)=\begin{cases}{\left |{x}\right |}&\text{if}& x \in \mathbb{Q}\\ 0 & \text{if}& x \not \in \mathbb{Q}\end{cases}$$ at the point zero. Participants emphasize that to show $$\lim_{x\to 0} f(x) = 0$$, one must demonstrate that for any sequence $$\{x_n\}$$ converging to zero, $$f(x_n)$$ also converges to zero. The proof requires using the formal definition of limits and continuity, specifically the epsilon-delta criterion, to establish that $$|f(x_n) - f(0)| < \epsilon$$ for sufficiently large $$n$$.
PREREQUISITES
- Understanding of limits and continuity in real analysis.
- Familiarity with piecewise functions and their properties.
- Knowledge of the epsilon-delta definition of limits.
- Ability to work with sequences and their convergence.
NEXT STEPS
- Study the epsilon-delta definition of continuity in detail.
- Learn how to prove limits using sequences in real analysis.
- Explore properties of piecewise functions and their continuity.
- Investigate examples of functions that are continuous at some points and discontinuous at others.
USEFUL FOR
Students of mathematics, particularly those studying real analysis, educators teaching calculus concepts, and anyone interested in understanding the formal proofs of continuity and limits.