1. **State the problem:**
We are given two polynomial functions:
- $y = 2x(x + 3)(x - 2)(x - 4)$
- $y = (x^2 + 3)(x^2 - 4)$
We need to find for each:
- Degree
- Zeros and their types
- Y-intercept
- End behavior
2. **Analyze the first polynomial:**
- The function is $y = 2x(x + 3)(x - 2)(x - 4)$.
- This is a product of four linear factors multiplied by 2.
**Degree:**
Each factor is degree 1, so total degree is $1 + 1 + 1 + 1 = 4$.
**Zeros and types:**
Set each factor equal to zero:
- $2x = 0 \Rightarrow x = 0$
- $x + 3 = 0 \Rightarrow x = -3$
- $x - 2 = 0 \Rightarrow x = 2$
- $x - 4 = 0 \Rightarrow x = 4$
All zeros are distinct and linear, so all are simple zeros (multiplicity 1).
**Y-intercept:**
Evaluate $y$ at $x=0$:
$$y = 2 \times 0 \times (0 + 3) \times (0 - 2) \times (0 - 4) = 0$$
So the y-intercept is 0.
**End behavior:**
Leading term is $2x^4$ (since multiplying all $x$ terms gives $x^4$ and coefficient 2).
- Since degree is even and leading coefficient positive, as $x \to \pm \infty$, $y \to +\infty$.
3. **Analyze the second polynomial:**
- The function is $y = (x^2 + 3)(x^2 - 4)$.
**Degree:**
Each factor is degree 2, so total degree is $2 + 2 = 4$.
**Zeros and types:**
Set each factor equal to zero:
- $x^2 + 3 = 0 \Rightarrow x^2 = -3$ no real zeros here.
- $x^2 - 4 = 0 \Rightarrow x^2 = 4 \Rightarrow x = \pm 2$
So zeros are $x = -2$ and $x = 2$, each with multiplicity 1 (since factors are linear in $x^2$).
**Y-intercept:**
Evaluate $y$ at $x=0$:
$$y = (0^2 + 3)(0^2 - 4) = 3 \times (-4) = -12$$
So the y-intercept is $-12$.
**End behavior:**
Leading term is $x^2 \times x^2 = x^4$ with coefficient 1 (positive).
- Since degree is even and leading coefficient positive, as $x \to \pm \infty$, $y \to +\infty$.
4. **Summary:**
| Function | Degree | Zeros | Y-intercept | End Behavior |
|---|---|---|---|---|
| $2x(x+3)(x-2)(x-4)$ | 4 | $x=0,-3,2,4$ (all simple) | 0 | $y \to +\infty$ as $x \to \pm \infty$ |
| $(x^2+3)(x^2-4)$ | 4 | $x=\pm 2$ (simple) | -12 | $y \to +\infty$ as $x \to \pm \infty$ |
5. **Graph shapes and math description:**
- Both are quartic polynomials with positive leading coefficients.
- The first has four distinct real roots, so the graph crosses the x-axis four times.
- The second has two real roots and two complex roots, so it crosses the x-axis twice.
- Both graphs rise to positive infinity on both ends.
Final answers:
- For $y = 2x(x + 3)(x - 2)(x - 4)$:
- Degree: 4
- Zeros: $-3, 0, 2, 4$ (all simple)
- Y-intercept: 0
- End behavior: $y \to +\infty$ as $x \to \pm \infty$
- For $y = (x^2 + 3)(x^2 - 4)$:
- Degree: 4
- Zeros: $-2, 2$ (simple)
- Y-intercept: -12
- End behavior: $y \to +\infty$ as $x \to \pm \infty$
Polynomial Characteristics 60E9A7
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