1. **Problem Statement:**
Given the rational function $$g(x) = \frac{2x^3 - 2x^2 + 8x - 8}{x^3 - x^2 - 9x + 9},$$ find the holes, horizontal asymptotes, vertical asymptotes, x-intercepts, y-intercepts, domain, range, and sketch the graph.
2. **Step 1: Factor numerator and denominator to find holes and asymptotes.**
Factor numerator:
$$2x^3 - 2x^2 + 8x - 8 = 2(x^3 - x^2 + 4x - 4).$$
Group terms:
$$x^3 - x^2 + 4x - 4 = (x^3 - x^2) + (4x - 4) = x^2(x - 1) + 4(x - 1) = (x - 1)(x^2 + 4).$$
So numerator factors as:
$$2(x - 1)(x^2 + 4).$$
Factor denominator:
$$x^3 - x^2 - 9x + 9 = (x^3 - x^2) - (9x - 9) = x^2(x - 1) - 9(x - 1) = (x - 1)(x^2 - 9).$$
Further factor:
$$x^2 - 9 = (x - 3)(x + 3).$$
So denominator factors as:
$$(x - 1)(x - 3)(x + 3).$$
3. **Step 2: Identify holes.**
Holes occur where factors cancel in numerator and denominator.
Common factor: $(x - 1)$.
So hole at $x = 1$.
4. **Step 3: Simplify function after canceling hole factor.**
$$g(x) = \frac{2\cancel{(x - 1)}(x^2 + 4)}{\cancel{(x - 1)}(x - 3)(x + 3)} = \frac{2(x^2 + 4)}{(x - 3)(x + 3)}.$$
5. **Step 4: Horizontal asymptotes.**
Degree numerator = 2, degree denominator = 2.
For equal degrees, horizontal asymptote is ratio of leading coefficients.
Leading coefficient numerator: $2$ (from $2x^2$ term).
Leading coefficient denominator: $1$ (from $x^2$ term).
So horizontal asymptote:
$$y = \frac{2}{1} = 2.$$
6. **Step 5: Vertical asymptotes.**
Vertical asymptotes occur where denominator is zero and not canceled.
Denominator factors: $(x - 3)(x + 3)$.
So vertical asymptotes at:
$$x = 3, \quad x = -3.$$
7. **Step 6: X-intercepts.**
Set numerator equal to zero:
$$2(x^2 + 4) = 0 \implies x^2 + 4 = 0 \implies x^2 = -4.$$
No real solutions, so no x-intercepts.
8. **Step 7: Y-intercept.**
Set $x=0$:
$$g(0) = \frac{2(0^2 + 4)}{(0 - 3)(0 + 3)} = \frac{2(4)}{-3 \times 3} = \frac{8}{-9} = -\frac{8}{9}.$$
So y-intercept at $(0, -\frac{8}{9})$.
9. **Step 8: Domain.**
Domain excludes values making denominator zero:
$$x \neq 1, 3, -3.$$
Note $x=1$ is a hole, so excluded.
10. **Step 9: Range.**
Range is all real numbers except the horizontal asymptote value $y=2$ because the function approaches but never reaches it.
11. **Step 10: Summary:**
- Holes: $x=1$
- Horizontal asymptote: $y=2$
- Vertical asymptotes: $x=3, x=-3$
- X-intercepts: none
- Y-intercept: $(0, -\frac{8}{9})$
- Domain: $\{x \in \mathbb{R} \mid x \neq -3, 1, 3\}$
- Range: $\{y \in \mathbb{R} \mid y \neq 2\}$
Rational Function Analysis 850F5B
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