Logistic Curve 9A8Bca
1. **Problem Statement:**
Consider the function $$P(x) = \frac{x^2}{x^2 + 4}$$.
We will analyze its domain, range, first and second derivatives, intervals of increase/decrease, concavity, inflection points, and asymptotes.
2. **Domain and Range:**
- The denominator $$x^2 + 4$$ is always positive since $$x^2 \geq 0$$ and 4 is positive.
- Therefore, the domain is all real numbers: $$(-\infty, \infty)$$.
- For the range, note that $$P(x) = \frac{x^2}{x^2 + 4}$$ is always between 0 and 1 because $$x^2 \geq 0$$ and $$x^2 + 4 > x^2$$.
- As $$x \to \pm \infty$$, $$P(x) \to 1$$.
- At $$x=0$$, $$P(0) = 0$$.
- Hence, the range is $$[0, 1)$$.
3. **First Derivative and Intervals of Increase/Decrease:**
- Use the quotient rule: $$P'(x) = \frac{(2x)(x^2 + 4) - x^2(2x)}{(x^2 + 4)^2}$$.
- Simplify numerator:
$$2x(x^2 + 4) - 2x^3 = 2x^3 + 8x - 2x^3 = 8x$$.
- So, $$P'(x) = \frac{8x}{(x^2 + 4)^2}$$.
- Critical point at $$x=0$$.
- For $$x < 0$$, $$P'(x) < 0$$ (decreasing).
- For $$x > 0$$, $$P'(x) > 0$$ (increasing).
4. **Second Derivative and Concavity/Inflection Points:**
- Differentiate $$P'(x)$$ using quotient rule:
$$P''(x) = \frac{8(x^2 + 4)^2 - 8x \cdot 2(x^2 + 4)(2x)}{(x^2 + 4)^4}$$.
- Simplify numerator:
$$8(x^2 + 4)^2 - 32x^2(x^2 + 4) = 8(x^2 + 4)[(x^2 + 4) - 4x^2] = 8(x^2 + 4)(4 - 3x^2)$$.
- So,
$$P''(x) = \frac{8(x^2 + 4)(4 - 3x^2)}{(x^2 + 4)^4} = \frac{8(4 - 3x^2)}{(x^2 + 4)^3}$$.
- Set numerator zero for inflection points:
$$4 - 3x^2 = 0 \Rightarrow x = \pm \frac{2}{\sqrt{3}}$$.
- Concave up where $$P''(x) > 0$$: when $$4 - 3x^2 > 0 \Rightarrow |x| < \frac{2}{\sqrt{3}}$$.
- Concave down where $$|x| > \frac{2}{\sqrt{3}}$$.
5. **Asymptotes:**
- Vertical asymptotes occur where denominator is zero; here, $$x^2 + 4 \neq 0$$ for all real $$x$$, so no vertical asymptotes.
- Horizontal asymptote as $$x \to \pm \infty$$:
$$\lim_{x \to \pm \infty} P(x) = \lim_{x \to \pm \infty} \frac{x^2}{x^2 + 4} = 1$$.
- So, horizontal asymptote at $$y = 1$$.
**Final answers:**
- Domain: $$(-\infty, \infty)$$
- Range: $$[0, 1)$$
- Increasing on $$(0, \infty)$$, decreasing on $$(-\infty, 0)$$
- Concave up on $$\left(-\frac{2}{\sqrt{3}}, \frac{2}{\sqrt{3}}\right)$$, concave down elsewhere
- Inflection points at $$x = \pm \frac{2}{\sqrt{3}}$$
- Horizontal asymptote at $$y=1$$, no vertical asymptotes
This completes the curve sketching analysis.