Limit Finding
1. Problem 49: Given $$\lim_{x \to 4} \frac{f(x) - 5}{x - 2} = 1$$, find $$\lim_{x \to 4} f(x)$$.
2. We use the property of limits and continuity. The expression resembles the definition of a derivative but here we focus on the limit of $$f(x)$$.
3. Substitute $$x = 4$$ in the denominator: $$4 - 2 = 2$$.
4. Rewrite the limit as $$\lim_{x \to 4} \frac{f(x) - 5}{2} = 1$$.
5. Multiply both sides by 2: $$\lim_{x \to 4} (f(x) - 5) = 2$$.
6. Add 5 to both sides: $$\lim_{x \to 4} f(x) = 7$$.
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7. Problem 50: Given $$\lim_{x \to -2} \frac{f(x)}{x^2} = 1$$.
(a) Find $$\lim_{x \to -2} f(x)$$.
(b) Find $$\lim_{x \to -2} \frac{f(x)}{x}$$.
8. For (a), since $$\lim_{x \to -2} \frac{f(x)}{x^2} = 1$$ and $$x^2$$ is continuous, $$\lim_{x \to -2} x^2 = (-2)^2 = 4$$.
9. Multiply both sides by 4: $$\lim_{x \to -2} f(x) = 1 \times 4 = 4$$.
10. For (b), $$\lim_{x \to -2} \frac{f(x)}{x} = \lim_{x \to -2} f(x) \times \lim_{x \to -2} \frac{1}{x} = 4 \times \frac{1}{-2} = -2$$.
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11. Problem 51:
(a) Given $$\lim_{x \to 2} \frac{f(x) - 5}{x - 2} = 3$$, find $$\lim_{x \to 2} f(x)$$.
(b) Given $$\lim_{x \to 2} \frac{f(x) - 5}{x - 2} = 4$$, find $$\lim_{x \to 2} f(x)$$.
12. Similar to problem 49, substitute $$x = 2$$ in denominator: $$2 - 2 = 0$$, but the limit exists, so numerator must approach 0.
13. Rewrite limit as $$\lim_{x \to 2} \frac{f(x) - 5}{x - 2} = L$$, where $$L$$ is 3 or 4.
14. Multiply both sides by $$x - 2$$ and take limit: $$\lim_{x \to 2} (f(x) - 5) = L \times 0 = 0$$.
15. So, $$\lim_{x \to 2} f(x) = 5$$ for both (a) and (b).
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16. Problem 52: Given $$\lim_{x \to 0} \frac{f(x)}{x^2} = 1$$.
(a) Find $$\lim_{x \to 0} f(x)$$.
(b) Find $$\lim_{x \to 0} \frac{f(x)}{x}$$.
17. For (a), since $$\lim_{x \to 0} \frac{f(x)}{x^2} = 1$$ and $$\lim_{x \to 0} x^2 = 0$$, multiply both sides by 0: $$\lim_{x \to 0} f(x) = 1 \times 0 = 0$$.
18. For (b), $$\lim_{x \to 0} \frac{f(x)}{x} = \lim_{x \to 0} f(x) \times \lim_{x \to 0} \frac{1}{x}$$.
19. But $$\lim_{x \to 0} \frac{1}{x}$$ does not exist (infinite), so the limit does not exist.
Final answers:
49. $$\lim_{x \to 4} f(x) = 7$$.
50. (a) $$4$$, (b) $$-2$$.
51. (a) $$5$$, (b) $$5$$.
52. (a) $$0$$, (b) does not exist.