Rational Function 81B04C
1. **Problem Statement:** Given the function $$F(x) = \frac{x + 5}{2 - x}$$, find:
i) Turning point (x, y)
ii) Line of symmetry
iii) Maximum or minimum value
iv) Draw the graph of $$F(x)$$
v) Deduce the domain and range
2. **Important Notes:**
- The function is a rational function with a vertical asymptote where the denominator is zero.
- Turning points occur where the derivative $$F'(x)$$ is zero.
- The line of symmetry for rational functions often relates to the vertical asymptote or the axis through the turning point.
3. **Step i) Find the turning point:**
- First, find the derivative $$F'(x)$$ using the quotient rule:
$$F(x) = \frac{u}{v} = \frac{x+5}{2-x}$$
$$u = x+5, \quad v = 2-x$$
$$u' = 1, \quad v' = -1$$
$$F'(x) = \frac{u'v - uv'}{v^2} = \frac{1 \cdot (2-x) - (x+5)(-1)}{(2-x)^2} = \frac{2 - x + x + 5}{(2-x)^2} = \frac{7}{(2-x)^2}$$
- Since $$F'(x) = \frac{7}{(2-x)^2} > 0$$ for all $$x \neq 2$$, the derivative never equals zero.
- Therefore, there is **no turning point**.
4. **Step ii) Line of symmetry:**
- The vertical asymptote is at $$x = 2$$ (where denominator is zero).
- The function is undefined at $$x=2$$ and the graph has two branches separated by this vertical line.
- This vertical asymptote $$x=2$$ acts as a line of symmetry for the hyperbola-like graph.
5. **Step iii) Max/Min value:**
- Since $$F'(x) > 0$$ everywhere except at $$x=2$$, the function is strictly increasing on each interval separated by $$x=2$$.
- There is no maximum or minimum value.
6. **Step iv) Graph of $$F(x)$$:**
- Vertical asymptote at $$x=2$$.
- Zero at $$x = -5$$ (numerator zero).
- Horizontal asymptote as $$x \to \pm \infty$$ is found by dividing numerator and denominator by $$x$$:
$$\lim_{x \to \pm \infty} F(x) = \lim_{x \to \pm \infty} \frac{1 + 5/x}{2/x - 1} = \frac{1 + 0}{0 - 1} = -1$$
- So horizontal asymptote is $$y = -1$$.
7. **Step v) Domain and range:**
- Domain: All real numbers except where denominator is zero:
$$\boxed{(-\infty, 2) \cup (2, \infty)}$$
- Range: Since the function approaches but never reaches $$y = -1$$ and is continuous on each interval, the range is:
$$\boxed{(-\infty, -1) \cup (-1, \infty)}$$
**Final answers:**
- Turning point: None
- Line of symmetry: $$x = 2$$
- Max/Min value: None
- Domain: $$(-\infty, 2) \cup (2, \infty)$$
- Range: $$(-\infty, -1) \cup (-1, \infty)$$