Polynomial Curves 383C5D
1. **Problem Statement:**
Sketch and analyze the curves for the following functions:
a) $y = x^2 (x + 2)$
c) $y = (x + 1)^2 (x - 2)$
a) $y = |(x + 1)(x - 2)(x - 3)|$
b) $y = x^2(5 - 2x)$
d) $y = (x - 2)^2(10 - 3x)$
2. **General Approach:**
- Identify zeros (roots) by setting the function equal to zero.
- Determine multiplicity of roots to understand if the graph touches or crosses the x-axis.
- Analyze end behavior by considering the degree and leading coefficient.
- For absolute value functions, reflect negative parts above the x-axis.
3. **Function a) $y = x^2 (x + 2)$:**
- Roots: $x=0$ (multiplicity 2), $x=-2$ (multiplicity 1).
- At $x=0$, the graph touches the x-axis and turns around (because of even multiplicity).
- At $x=-2$, the graph crosses the x-axis.
- Degree: 3 (odd), leading term $x^3$, so as $x \to \infty$, $y \to \infty$; as $x \to -\infty$, $y \to -\infty$.
4. **Function c) $y = (x + 1)^2 (x - 2)$:**
- Roots: $x=-1$ (multiplicity 2), $x=2$ (multiplicity 1).
- At $x=-1$, graph touches and turns.
- At $x=2$, graph crosses.
- Degree: 3 (odd), leading term $x^3$, same end behavior as above.
5. **Function a) $y = |(x + 1)(x - 2)(x - 3)|$:**
- Roots: $x=-1, 2, 3$.
- Without absolute value, graph crosses x-axis at these points.
- Absolute value reflects any negative values above x-axis, so graph never goes below x-axis.
- Degree: 3 (odd), but graph is always $\geq 0$.
6. **Function b) $y = x^2(5 - 2x)$:**
- Roots: $x=0$ (multiplicity 2), $x=\frac{5}{2}$ (multiplicity 1).
- At $x=0$, graph touches and turns.
- At $x=\frac{5}{2}$, graph crosses.
- Degree: 3 (odd), leading term $-2x^3$, so as $x \to \infty$, $y \to -\infty$; as $x \to -\infty$, $y \to \infty$.
7. **Function d) $y = (x - 2)^2(10 - 3x)$:**
- Roots: $x=2$ (multiplicity 2), $x=\frac{10}{3}$ (multiplicity 1).
- At $x=2$, graph touches and turns.
- At $x=\frac{10}{3}$, graph crosses.
- Degree: 3 (odd), leading term $-3x^3$, same end behavior as function b).
**Summary:**
- For each polynomial, roots and their multiplicities determine x-intercept behavior.
- Odd degree polynomials have opposite end behaviors depending on leading coefficient sign.
- Absolute value modifies the graph by reflecting negative parts above x-axis.
Final answers are the sketches and analysis as described above.