Math Problem Statement

A polynomial f (x) = ax3 – bx2 + 3, where a and b are nonzero, real constants. The function f has an x-intercept at (–5.94, 0) and a root at –0.27 – 0.07i. Which of the following statements is true?

The graph of the function f has a total of three x-intercepts. The function f has three real solutions. A zero of f is 0.27 + 0.07i. A zero of f is –0.27 + 0.07i.

Solution

Let's break down the given information and use it to find the correct answer step by step.

Information Given:

  1. The polynomial is f(x)=ax3bx2+3f(x) = ax^3 - bx^2 + 3, where aa and bb are nonzero real constants.
  2. The function has an x-intercept at (5.94,0)(-5.94, 0). This means that x=5.94x = -5.94 is a real root of f(x)f(x).
  3. The function has a root at 0.270.07i-0.27 - 0.07i, which is a complex number.

Step 1: Understanding the nature of the roots

Since f(x)f(x) is a cubic polynomial (degree 3), it can have:

  • 3 real roots, or
  • 1 real root and 2 complex roots.

However, complex roots for polynomials with real coefficients always come in conjugate pairs. This means that if 0.270.07i-0.27 - 0.07i is a root, its conjugate 0.27+0.07i-0.27 + 0.07i must also be a root.

Step 2: Finding the number of real and complex roots

The function has:

  • One known real root at x=5.94x = -5.94.
  • Two complex roots: 0.270.07i-0.27 - 0.07i and 0.27+0.07i-0.27 + 0.07i.

Thus, the function has exactly one real root and two complex roots.

Step 3: Evaluating the options

  • Option 1: "The graph of the function ff has a total of three x-intercepts."

    • Incorrect. The function has only one real root and two complex roots, which means it has only one x-intercept.
  • Option 2: "The function ff has three real solutions."

    • Incorrect. As we determined, the function has one real root and two complex roots, not three real solutions.
  • Option 3: "A zero of ff is 0.27+0.07i0.27 + 0.07i."

    • Incorrect. The complex root is 0.27+0.07i-0.27 + 0.07i, not 0.27+0.07i0.27 + 0.07i.
  • Option 4: "A zero of ff is 0.27+0.07i-0.27 + 0.07i."

    • Correct! This is the conjugate pair of 0.270.07i-0.27 - 0.07i, and thus a valid zero of f(x)f(x).

Final Answer:

The correct statement is:

  • A zero of ff is 0.27+0.07i-0.27 + 0.07i.

Would you like further details or clarification on any part of this solution?

Here are 5 related questions to consider:

  1. How do complex roots affect the shape of a cubic polynomial graph?
  2. What is the relationship between complex conjugates and real coefficients?
  3. How do you determine the number of real vs complex roots in a cubic function?
  4. What happens to the real root if the polynomial has more than one complex pair?
  5. How can we factor a cubic polynomial when complex roots are involved?

Tip: For any polynomial with real coefficients, if it has a complex root, its conjugate must also be a root.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Cubic Polynomials
Complex Roots
Conjugate Pairs

Formulas

Cubic polynomial root relationships
Complex number conjugates

Theorems

Fundamental Theorem of Algebra

Suitable Grade Level

Grades 11-12