Question: 3. Complete Function Analysis
Analyze the function:
$$g(x) = \frac{(x+1)^2(x-4)}{(x+1)(x^2 -16)}$$
(a)
i. Factor completely and simplify if possible.
ii. Find the domain.
(b) i. Identify all asymptotes and holes.
ii. Find all intercepts.
(c)
i. Determine where the function is positive/negative.
ii. Sketch the graph showing all key features (including any holes).
1. **State the problem:**
We analyze the function $$g(x) = \frac{(x+1)^2(x-4)}{(x+1)(x^2 -16)}$$ including factoring, domain, asymptotes, holes, intercepts, sign, and graph.
2. **Factor completely and simplify:**
- Factor denominator: $$x^2 -16 = (x-4)(x+4)$$
- Rewrite $$g(x) = \frac{(x+1)^2 (x-4)}{(x+1)(x-4)(x+4)}$$
- Cancel common factors:
$$g(x) = \frac{\cancel{(x+1)} (x+1) \cancel{(x-4)}}{\cancel{(x+1)} \cancel{(x-4)} (x+4)} = \frac{x+1}{x+4}$$
3. **Find the domain:**
- Original denominator zeroes: $$x+1=0 \Rightarrow x=-1$$, $$x-4=0 \Rightarrow x=4$$, $$x+4=0 \Rightarrow x=-4$$
- Domain excludes $$x=-1, 4, -4$$
4. **Identify asymptotes and holes:**
- Holes occur where factors canceled:
- At $$x=-1$$ and $$x=4$$ (since these factors canceled)
- Vertical asymptote where denominator zero remains:
- At $$x=-4$$
- Horizontal asymptote:
- Simplified function $$g(x) = \frac{x+1}{x+4}$$ has degree 1 numerator and denominator.
- Horizontal asymptote is $$y=\frac{1}{1}=1$$
5. **Find intercepts:**
- x-intercept: numerator zero $$x+1=0 \Rightarrow x=-1$$ (hole, not intercept)
- y-intercept: evaluate at $$x=0$$:
$$g(0) = \frac{0+1}{0+4} = \frac{1}{4}$$
6. **Determine where function is positive/negative:**
- Simplified function $$g(x) = \frac{x+1}{x+4}$$ with domain excluding $$-4, -1, 4$$
- Sign depends on numerator and denominator:
- Numerator zero at $$x=-1$$ (hole)
- Denominator zero at $$x=-4$$ (vertical asymptote)
- Test intervals:
- $$(-\infty, -4)$$: numerator negative, denominator negative, fraction positive
- $$(-4, -1)$$: numerator negative, denominator positive, fraction negative
- $$(-1, \infty)$$: numerator positive, denominator positive, fraction positive
7. **Sketch the graph:**
- Vertical asymptote at $$x=-4$$
- Holes at $$x=-1$$ and $$x=4$$
- Horizontal asymptote at $$y=1$$
- Function simplified to $$\frac{x+1}{x+4}$$ except holes
- y-intercept at $$\left(0, \frac{1}{4}\right)$$
Final answer:
$$g(x) = \frac{x+1}{x+4}$$ with domain $$x \neq -4, -1, 4$$, vertical asymptote at $$x=-4$$, holes at $$x=-1$$ and $$x=4$$, horizontal asymptote $$y=1$$, positive on $$(-\infty,-4) \cup (-1, \infty)$$, negative on $$(-4,-1)$$.