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A polynomial with a double root at \(-2\) and another root at \(5\) is:
\[
f(x) = (x + 2)^2(x - 5)
\]
Expanding it gives:
\[
f(x) = x^3 - x^2 - 16x - 20
\]
You can adjust the leading coefficient \(a\) to scale the polynomial as desired.
Solución
To construct a polynomial function with a **double root at \(-2\)** and another root at \(5\), you can follow these steps:
### 1. **Understanding Roots and Multiplicity**
- A **double root** at \(-2\) means that \((x + 2)\) is a factor **twice**.
- A **single root** at \(5\) means that \((x - 5)\) is a factor **once**.
### 2. **Constructing the Polynomial**
Combine these factors to form the polynomial:
\[
f(x) = a(x + 2)^2(x - 5)
\]
where \(a\) is any non-zero constant (it determines the leading coefficient and can scale the polynomial vertically).
### 3. **Expanding the Polynomial (Optional)**
If you prefer the expanded form, you can multiply the factors:
\[
\begin{align*}
f(x) &= a(x + 2)^2(x - 5) \\
&= a(x^2 + 4x + 4)(x - 5) \\
&= a\left(x^3 + 4x^2 + 4x - 5x^2 - 20x - 20\right) \\
&= a\left(x^3 - x^2 - 16x - 20\right) \\
&= a x^3 - a x^2 - 16a x - 20a
\end{align*}
\]
### 4. **Example Polynomial**
For simplicity, let’s choose \(a = 1\):
\[
f(x) = (x + 2)^2(x - 5) = x^3 - x^2 - 16x - 20
\]
### 5. **General Form**
Any polynomial with the specified roots can be written as:
\[
f(x) = a(x + 2)^2(x - 5) \quad \text{where} \quad a \neq 0
\]
You can choose different values of \(a\) to get different polynomial functions that satisfy the root conditions.
### **Graphical Interpretation**
- **Double Root at \(-2\):** The graph of the polynomial will touch the x-axis at \(x = -2\) and turn around, indicating a repeated root.
- **Single Root at \(5\):** The graph will cross the x-axis at \(x = 5\).
### **Summary**
A suitable polynomial with a double root at \(-2\) and another root at \(5\) is:
\[
f(x) = (x + 2)^2(x - 5)
\]
You can expand it to:
\[
f(x) = x^3 - x^2 - 16x - 20
\]
Feel free to choose any non-zero constant \(a\) to scale the polynomial as needed.
Revisado y aprobado por el equipo de tutoría de UpStudy
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