Indeterminate Form
1. **Stating the problem:** We want to understand what an indeterminate form is in calculus and see a numerical example.
2. **Definition:** An indeterminate form occurs when evaluating a limit results in an expression like $\frac{0}{0}$ or $\frac{\infty}{\infty}$, which does not directly tell us the limit's value.
3. **Common indeterminate forms:** $0/0$, $\infty/\infty$, $0 \times \infty$, $\infty - \infty$, $0^0$, $1^\infty$, and $\infty^0$.
4. **Example:** Consider the function $f(x) = \frac{x^2 - 4}{x - 2}$ and find $\lim_{x \to 2} f(x)$.
5. **Direct substitution:** Substitute $x=2$:
$$\frac{2^2 - 4}{2 - 2} = \frac{4 - 4}{0} = \frac{0}{0}$$ which is an indeterminate form.
6. **Resolving the indeterminate form:** Factor numerator:
$$x^2 - 4 = (x - 2)(x + 2)$$
7. **Simplify the function:**
$$f(x) = \frac{(x - 2)(x + 2)}{x - 2}$$
For $x \neq 2$, this simplifies to:
$$f(x) = x + 2$$
8. **Evaluate the limit:** Now,
$$\lim_{x \to 2} f(x) = \lim_{x \to 2} (x + 2) = 2 + 2 = 4$$
9. **Conclusion:** Although direct substitution gave an indeterminate form $\frac{0}{0}$, simplifying the function allowed us to find the limit is 4.
This illustrates how indeterminate forms require algebraic manipulation or other techniques to evaluate limits.