K Find a polynomial function of degree 3 with the given numbers as zeros. Assume that the leading coefficient is 1. -3, 4i, -4i The polynomial function is f(x)= (Simplify your answer. Use integers or fractions for any numbers in the expression.)

Algebra and Trigonometry (6th Edition)
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ChapterP: Prerequisites: Fundamental Concepts Of Algebra
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Problem 1MCCP: In Exercises 1-25, simplify the given expression or perform the indicated operation (and simplify,...
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**Task:**

Find a polynomial function of degree 3 with the given numbers as zeros. Assume that the leading coefficient is 1.

**Zeros:**  
\( -3, 4i, -4i \)

**Instructions:**  
The polynomial function is \( f(x) = \, \_\_ \)

(Simplify your answer. Use integers or fractions for any numbers in the expression.)

---

**Explanation:**

To construct the polynomial, use the fact that if \( a \) is a zero, then \( (x-a) \) is a factor of the polynomial. Since complex zeros occur in conjugate pairs, both \( 4i \) and \( -4i \) must be used.

### Factors:

- \( (x + 3) \) for the zero \( -3 \)
- \( (x - 4i) \) for the zero \( 4i \)
- \( (x + 4i) \) for the zero \( -4i \)

### Polynomial Expansion:

1. Multiply the complex factors:
   \[
   (x - 4i)(x + 4i) = x^2 - (4i)^2 = x^2 + 16
   \]
   (since \( (i)^2 = -1 \) and thus \( (4i)^2 = -16 \))

2. Multiply with the real factor:
   \[
   f(x) = (x + 3)(x^2 + 16)
   \]
   Expand further:
   \[
   f(x) = x(x^2 + 16) + 3(x^2 + 16) \\
   = x^3 + 16x + 3x^2 + 48
   \]

3. Simplify:
   \[
   f(x) = x^3 + 3x^2 + 16x + 48
   \]

Thus, the polynomial function is:
\[ f(x) = x^3 + 3x^2 + 16x + 48 \]
Transcribed Image Text:**Task:** Find a polynomial function of degree 3 with the given numbers as zeros. Assume that the leading coefficient is 1. **Zeros:** \( -3, 4i, -4i \) **Instructions:** The polynomial function is \( f(x) = \, \_\_ \) (Simplify your answer. Use integers or fractions for any numbers in the expression.) --- **Explanation:** To construct the polynomial, use the fact that if \( a \) is a zero, then \( (x-a) \) is a factor of the polynomial. Since complex zeros occur in conjugate pairs, both \( 4i \) and \( -4i \) must be used. ### Factors: - \( (x + 3) \) for the zero \( -3 \) - \( (x - 4i) \) for the zero \( 4i \) - \( (x + 4i) \) for the zero \( -4i \) ### Polynomial Expansion: 1. Multiply the complex factors: \[ (x - 4i)(x + 4i) = x^2 - (4i)^2 = x^2 + 16 \] (since \( (i)^2 = -1 \) and thus \( (4i)^2 = -16 \)) 2. Multiply with the real factor: \[ f(x) = (x + 3)(x^2 + 16) \] Expand further: \[ f(x) = x(x^2 + 16) + 3(x^2 + 16) \\ = x^3 + 16x + 3x^2 + 48 \] 3. Simplify: \[ f(x) = x^3 + 3x^2 + 16x + 48 \] Thus, the polynomial function is: \[ f(x) = x^3 + 3x^2 + 16x + 48 \]
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