Rational Linear Functions
1. **Problem a: Analyze and graph** $f(x) = \frac{2x - 1}{x^2 - 4}$.
2. **Domain:** The function is undefined where the denominator is zero: solve $x^2 - 4 = 0$ which gives $x = \pm 2$. So,
$$\text{Domain} = \{ x \in \mathbb{R} \mid x \neq -2, x \neq 2 \}.$$
3. **Vertical asymptotes:** At points where the denominator is zero but numerator is not zero.
- At $x = -2$, numerator $2(-2) - 1 = -4 - 1 = -5 \neq 0$ vertical asymptote.
- At $x = 2$, numerator $2(2) - 1 = 4 - 1 = 3 \neq 0$ vertical asymptote.
So vertical asymptotes at $x = -2$ and $x = 2$.
4. **Horizontal asymptote:** Compare degree of numerator (1) and denominator (2).
Since degree denominator > numerator, horizontal asymptote is $y = 0$.
5. **Intercepts:**
- **x-intercept**: Set numerator zero: $2x - 1 = 0 \Rightarrow x = \frac{1}{2}$.
- **y-intercept**: Evaluate at $x=0$:
$$f(0) = \frac{2(0) - 1}{0^2 - 4} = \frac{-1}{-4} = \frac{1}{4} = 0.25.$$
(Note: Given approx -0.25 is likely a typo; mathematical evaluation shows $0.25$.)
6. **Range:** Because of vertical asymptotes and shape, $f(x)$ takes all real values except possibly values around horizontal asymptote.
More detailed analysis shows range is $\mathbb{R}$ except possibly $y=0$, which is the horizontal asymptote but function can approach zero arbitrarily closely.
7. **Summary for a:**
- Domain: $x \neq \pm 2$
- Vertical asymptotes: $x = -2, 2$
- Horizontal asymptote: $y=0$
- x-intercept: $x=\frac{1}{2}$
- y-intercept: $y=0.25$
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8. **Problem b: Analyze and graph** $f(x) = \frac{1}{2}x + 20$.
9. **Domain:** All real numbers.
10. **Intercepts:**
- y-intercept at $x=0$: $f(0)=20$.
- x-intercept where $f(x)=0$:
$$0 = \frac{1}{2}x + 20 \Rightarrow x = -40.$$
11. **Range:** Since linear with slope $\frac{1}{2}$, range is all real numbers.
12. **Asymptotes:** None, linear function.
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13. **Problem c: Analyze and graph** $f(x) = \frac{2x}{6} - 5$.
14. **Simplify:**
$$f(x) = \frac{1}{3}x - 5.$$
15. **Domain:** All real numbers.
16. **Intercepts:**
- y-intercept at $x=0$: $f(0) = -5$.
- x-intercept where $f(x) = 0$:
$$0 = \frac{1}{3}x - 5 \Rightarrow x = 15.$$
17. **Range:** All real numbers.
18. **Asymptotes:** None, linear function.
**Final summary:**
- (a) Rational function with vertical asymptotes at $x=\pm 2$, horizontal asymptote at $y=0$, domain excludes $\pm 2$, intercepts at $x=0.5$ and $y=0.25$.
- (b) Linear function with slope $\frac{1}{2}$, y-intercept 20, x-intercept $-40$, domain and range all real numbers.
- (c) Linear function simplified to $f(x) = \frac{1}{3}x - 5$, y-intercept $-5$, x-intercept $15$, domain and range all real numbers.