Limit At 1
1. **State the problem:** We need to find the limits of the function $$f(x) = \frac{1 - 2x}{x^2 - 1}$$ as $$x$$ approaches $$-1$$ from the left ($$x \to -1^-$$), from the right ($$x \to -1^+$$), and the overall limit $$x \to -1$$.
2. **Factor the denominator:** The denominator can be factored as $$x^2 - 1 = (x-1)(x+1)$$.
3. **Rewrite the function:**
$$f(x) = \frac{1 - 2x}{(x-1)(x+1)}$$
4. **Evaluate the behavior as $$x \to -1$$:**
Substitute $$x = -1$$ in numerator:
$$1 - 2(-1) = 1 + 2 = 3$$
Substitute $$x = -1$$ in denominator:
$$(x-1)(x+1) = (-1 - 1)(-1 + 1) = (-2)(0) = 0$$
The denominator approaches zero, numerator approaches 3, so the function approaches infinity or negative infinity.
5. **Check the sign of the denominator near $$x = -1$$:**
- For $$x \to -1^-$$ (values slightly less than -1):
- $$x-1$$ is slightly less than $$-2$$ (negative)
- $$x+1$$ is slightly less than $$0$$ (negative)
- Product of two negatives is positive
- For $$x \to -1^+$$ (values slightly greater than -1):
- $$x-1$$ is slightly less than $$0$$ (negative)
- $$x+1$$ is slightly greater than $$0$$ (positive)
- Product of negative and positive is negative
6. **Calculate limits:**
(a) $$\lim_{x \to -1^-} f(x) = \lim_{x \to -1^-} \frac{3}{\text{positive small}} = +\infty$$
(b) $$\lim_{x \to -1^+} f(x) = \lim_{x \to -1^+} \frac{3}{\text{negative small}} = -\infty$$
(c) Since the left- and right-hand limits are not equal, $$\lim_{x \to -1} f(x)$$ does not exist.
**Final answers:**
$$\lim_{x \to -1^-} f(x) = +\infty$$
$$\lim_{x \to -1^+} f(x) = -\infty$$
$$\lim_{x \to -1} f(x) \text{ does not exist}$$