3 and 2i (fully expand the polynomial function) Polynomial Function:

Calculus: Early Transcendentals
8th Edition
ISBN:9781285741550
Author:James Stewart
Publisher:James Stewart
Chapter1: Functions And Models
Section: Chapter Questions
Problem 1RCC: (a) What is a function? What are its domain and range? (b) What is the graph of a function? (c) How...
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Find the polynomial function that has the following zeros
**Complex Roots and Polynomial Expansion**

**Problem:**

Given the roots 3 and 2i, fully expand the polynomial function.

**Solution Requirement:**

Find the polynomial function given these roots.

**Transcription:**

Polynomial Function: _______________

---

### Explanation:

When given roots such as 3 and 2i, a polynomial with real coefficients must also include the complex conjugate of any non-real root. Therefore, for root 2i, its conjugate -2i must also be included. 

### Steps:

1. **Identify the roots:**  
   - Real root: \( x = 3 \)  
   - Complex roots: \( x = 2i \) and \( x = -2i \)

2. **Form factors from roots:**  
   - Real root => \( (x - 3) \)  
   - Complex roots => \( (x - 2i)(x + 2i) \)

3. **Expand the complex roots factor:**  
   - \( (x - 2i)(x + 2i) \) = \( x^2 + 4 \) (Using the difference of squares: \( a^2 - b^2 = (a - b)(a + b) \))

4. **Combine all factors to form the polynomial:**  
   - Multiply \( (x - 3) \) by \( (x^2 + 4) \)

5. **Fully expand the polynomial:**
   \[
   P(x) = (x - 3)(x^2 + 4) = x^3 + 4x - 3x^2 - 12
   \]

Hence, the polynomial function is given by:
\[
P(x) = x^3 - 3x^2 + 4x - 12
\]
Transcribed Image Text:**Complex Roots and Polynomial Expansion** **Problem:** Given the roots 3 and 2i, fully expand the polynomial function. **Solution Requirement:** Find the polynomial function given these roots. **Transcription:** Polynomial Function: _______________ --- ### Explanation: When given roots such as 3 and 2i, a polynomial with real coefficients must also include the complex conjugate of any non-real root. Therefore, for root 2i, its conjugate -2i must also be included. ### Steps: 1. **Identify the roots:** - Real root: \( x = 3 \) - Complex roots: \( x = 2i \) and \( x = -2i \) 2. **Form factors from roots:** - Real root => \( (x - 3) \) - Complex roots => \( (x - 2i)(x + 2i) \) 3. **Expand the complex roots factor:** - \( (x - 2i)(x + 2i) \) = \( x^2 + 4 \) (Using the difference of squares: \( a^2 - b^2 = (a - b)(a + b) \)) 4. **Combine all factors to form the polynomial:** - Multiply \( (x - 3) \) by \( (x^2 + 4) \) 5. **Fully expand the polynomial:** \[ P(x) = (x - 3)(x^2 + 4) = x^3 + 4x - 3x^2 - 12 \] Hence, the polynomial function is given by: \[ P(x) = x^3 - 3x^2 + 4x - 12 \]
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