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:
- The polynomial is , where and are nonzero real constants.
- The function has an x-intercept at . This means that is a real root of .
- The function has a root at , which is a complex number.
Step 1: Understanding the nature of the roots
Since 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 is a root, its conjugate must also be a root.
Step 2: Finding the number of real and complex roots
The function has:
- One known real root at .
- Two complex roots: and .
Thus, the function has exactly one real root and two complex roots.
Step 3: Evaluating the options
-
Option 1: "The graph of the function 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 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 is ."
- Incorrect. The complex root is , not .
-
Option 4: "A zero of is ."
- Correct! This is the conjugate pair of , and thus a valid zero of .
Final Answer:
The correct statement is:
- A zero of is .
Would you like further details or clarification on any part of this solution?
Here are 5 related questions to consider:
- How do complex roots affect the shape of a cubic polynomial graph?
- What is the relationship between complex conjugates and real coefficients?
- How do you determine the number of real vs complex roots in a cubic function?
- What happens to the real root if the polynomial has more than one complex pair?
- 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.
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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