Limits Evaluation
1. **Problem 1:** Find the limit $$\lim_{x \to 0} \left(1 + \frac{1}{x}\right)^x$$.
2. **Step 1:** Recognize that as $$x \to 0$$, the expression inside the parentheses $$1 + \frac{1}{x}$$ becomes unbounded, and the exponent $$x$$ approaches 0. This is an indeterminate form of type $$1^\infty$$.
3. **Step 2:** Use the substitution $$t = \frac{1}{x}$$, so as $$x \to 0$$, $$t \to \pm \infty$$ depending on the direction.
4. **Step 3:** Rewrite the limit as $$\lim_{t \to \pm \infty} \left(1 + t\right)^{\frac{1}{t}}$$.
5. **Step 4:** For $$t \to +\infty$$, $$1 + t \to +\infty$$ and the exponent $$\frac{1}{t} \to 0^+$$. The expression behaves like $$\infty^0$$, which is indeterminate.
6. **Step 5:** Consider the natural logarithm:
$$\ln y = \frac{1}{t} \ln(1 + t)$$.
7. **Step 6:** As $$t \to +\infty$$, $$\ln(1 + t) \sim \ln t$$, so
$$\ln y \sim \frac{\ln t}{t}$$.
8. **Step 7:** Since $$\lim_{t \to +\infty} \frac{\ln t}{t} = 0$$, we have $$\ln y \to 0$$, so $$y \to e^0 = 1$$.
9. **Step 8:** For $$t \to -\infty$$, $$1 + t$$ is negative and the expression is not defined for real numbers, so the limit from the left does not exist.
10. **Answer 1:** The limit $$\lim_{x \to 0^+} \left(1 + \frac{1}{x}\right)^x = 1$$, and the limit from the left does not exist.
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11. **Problem 2:** Find the limit $$\lim_{x \to 1} \frac{x^2 - 1}{x - 1}$$.
12. **Step 1:** Notice direct substitution gives $$\frac{1 - 1}{1 - 1} = \frac{0}{0}$$, an indeterminate form.
13. **Step 2:** Factor numerator:
$$x^2 - 1 = (x - 1)(x + 1)$$.
14. **Step 3:** Simplify the expression:
$$\frac{(x - 1)(x + 1)}{x - 1} = x + 1, \quad x \neq 1$$.
15. **Step 4:** Now substitute $$x = 1$$:
$$1 + 1 = 2$$.
16. **Answer 2:** The limit is $$2$$.
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17. **Problem 3:** Find the limit $$\lim_{x \to 3} \frac{|x - 3|}{x - 3}$$.
18. **Step 1:** Consider the left-hand limit $$x \to 3^-$$:
When $$x < 3$$, $$x - 3 < 0$$, so $$|x - 3| = -(x - 3)$$.
19. **Step 2:** Substitute:
$$\frac{|x - 3|}{x - 3} = \frac{-(x - 3)}{x - 3} = -1$$.
20. **Step 3:** Consider the right-hand limit $$x \to 3^+$$:
When $$x > 3$$, $$x - 3 > 0$$, so $$|x - 3| = x - 3$$.
21. **Step 4:** Substitute:
$$\frac{|x - 3|}{x - 3} = \frac{x - 3}{x - 3} = 1$$.
22. **Step 5:** Since the left-hand limit is $$-1$$ and the right-hand limit is $$1$$, the two-sided limit does not exist.
23. **Answer 3:** The limit does not exist because the left and right limits differ.