data/knowledge_base/calculus.md

# Calculus – Basic Overview

## Limits
lim (x → a) f(x)

- Check left-hand and right-hand limits
- Limit exists only if both are equal

## Continuity
A function is continuous at x = a if:
1. f(a) exists
2. lim (x → a) f(x) exists
3. lim (x → a) f(x) = f(a)

## Applications
- Tangents
- Rate of change
- Optimization

## Common Mistakes
- Direct substitution without checking form