1. **Problem Statement:** We analyze the population growth of Green Leaf Beetles and Red Bark Beetles over time $t$ (in hours).
2. **Given Functions:**
- Green Leaf Beetles: $g(t) = t^2 + 30t + 200$
- Red Bark Beetles: $r(t) = t^2 + 180t + 150$
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### 1.1 Initial Population
- Initial population means population at $t=0$.
- For Green Leaf Beetles: $g(0) = 0^2 + 30\times0 + 200 = 200$
- For Red Bark Beetles: $r(0) = 0^2 + 180\times0 + 150 = 150$
### 1.2 Time when populations are equal
- Set $g(t) = r(t)$:
$$t^2 + 30t + 200 = t^2 + 180t + 150$$
- Simplify:
$$30t + 200 = 180t + 150$$
$$200 - 150 = 180t - 30t$$
$$50 = 150t$$
$$t = \frac{50}{150} = \frac{1}{3} \approx 0.333 \text{ hours}$$
### 1.3 Graphical Representation
- The populations are equal at $t \approx 0.333$ hours.
- On a graph, the curves $g(t)$ and $r(t)$ intersect at this point.
### 1.4 Behavior of Green Leaf Beetles as $t \to \infty$
- The dominant term is $t^2$.
- As $t$ increases, $g(t) \approx t^2$ grows without bound (quadratic growth).
- So, population increases rapidly to infinity.
### 1.5 Type of function for Red Bark Beetles
- $r(t) = t^2 + 180t + 150$ is a quadratic function (polynomial of degree 2).
### 1.6 Domain and Range of $r(t)$
- Domain: All real numbers $t$ since polynomial functions are defined everywhere.
- Range: Since the leading coefficient of $t^2$ is positive, the parabola opens upward.
- Vertex at $t = -\frac{b}{2a} = -\frac{180}{2} = -90$.
- Minimum value at vertex:
$$r(-90) = (-90)^2 + 180(-90) + 150 = 8100 - 16200 + 150 = -5950$$
- Range is $[-5950, \infty)$.
### 1.7 New growth function for Red Bark Beetles
- New function: $g_{new}(t) = 150 e^{2t}$
- Find $t$ when $g_{new}(t) > r(t)$:
$$150 e^{2t} > t^2 + 180t + 150$$
- At $t=0$, $g_{new}(0) = 150$, $r(0) = 150$ equal.
- For large $t$, exponential dominates polynomial.
- Approximate by testing values or solving numerically:
- At $t=1$: $150 e^{2} \approx 150 \times 7.389 = 1108.35$, $r(1) = 1 + 180 + 150 = 331$ so $g_{new}(1) > r(1)$.
- So, $g_{new}(t)$ surpasses $r(t)$ shortly after $t=0$.
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**Final answers:**
- Initial populations: Green Leaf Beetles = 200, Red Bark Beetles = 150
- Populations equal at $t = \frac{1}{3}$ hours
- Graph intersection at $t \approx 0.333$
- Green Leaf Beetles grow quadratically to infinity as $t \to \infty$
- Red Bark Beetles growth modeled by quadratic function
- Domain of $r(t)$: $(-\infty, \infty)$; Range: $[-5950, \infty)$
- New growth function surpasses initial function just after $t=0$
Insect Population Growth
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