Math Problem Statement

A polynomial f(x) = ax^3 - bx^2 + 3, where a and b are nonzero, real constants. The function has an x-intercept at (-5.94, 0) and a root at -0.27 - 0.07i. Which of the following statements is true?

Solution

Let's analyze the information provided in the image:

Given:

  • A polynomial f(x)=ax3bx2+3f(x) = ax^3 - bx^2 + 3, where aa and bb are nonzero, real constants.
  • The function has:
    • an x-intercept at (5.94,0)(-5.94, 0)
    • a root at 0.270.07i-0.27 - 0.07i

Question:

Which of the following statements is true?

Options:

  1. The graph of the function ff has a total of three x-intercepts.
  2. The function ff has three real solutions.
  3. A zero of ff is 0.27+0.07i0.27 + 0.07i.
  4. A zero of ff is 0.27+0.07i-0.27 + 0.07i.

Explanation:

The polynomial is cubic (x3x^3 term present), so it can have up to three roots (real or complex). The key details are:

  • One real root is given at (5.94,0)(-5.94, 0), which means one real x-intercept.
  • A complex root 0.270.07i-0.27 - 0.07i is also given. For polynomials with real coefficients, complex roots occur in conjugate pairs. Therefore, the root 0.270.07i-0.27 - 0.07i implies the presence of its conjugate pair, 0.27+0.07i-0.27 + 0.07i.

Option 1:

  • Incorrect. Since there are two complex roots (one conjugate pair) and one real root, there will be only one x-intercept, not three.

Option 2:

  • Incorrect. The function does not have three real solutions because two of the roots are complex.

Option 3:

  • Incorrect. The complex root is 0.270.07i-0.27 - 0.07i, not 0.27+0.07i0.27 + 0.07i.

Option 4:

  • Correct. The conjugate root to 0.270.07i-0.27 - 0.07i is 0.27+0.07i-0.27 + 0.07i, so this is true.

Final Answer:

The correct statement is Option 4: A zero of ff is 0.27+0.07i-0.27 + 0.07i.


Do you have any questions or would you like a deeper explanation?

Here are 5 related questions you can explore:

  1. How do you determine the number of real roots in a cubic function?
  2. Why do complex roots always come in conjugate pairs in polynomials with real coefficients?
  3. How can you graph a cubic function with both real and complex roots?
  4. What role does the discriminant play in finding the nature of the roots of a cubic equation?
  5. How do the coefficients aa and bb in the polynomial affect its shape and roots?

Tip: Always check the conjugate pair property when dealing with complex roots in polynomials with real coefficients.

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Math Problem Analysis

Mathematical Concepts

Algebra
Polynomials
Cubic Functions
Complex Numbers

Formulas

Cubic function
Complex root conjugate pair property

Theorems

Conjugate Root Theorem

Suitable Grade Level

Grades 10-12