Determine the different possibilities for the numbers of positive, negative, and nonreal complex zeros of each function.
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- 0. Review of Algebra4h 18m
- 1. Equations & Inequalities3h 18m
- 2. Graphs of Equations1h 43m
- 3. Functions2h 17m
- 4. Polynomial Functions1h 44m
- 5. Rational Functions1h 23m
- 6. Exponential & Logarithmic Functions2h 28m
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- 9. Sequences, Series, & Induction1h 22m
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4. Polynomial Functions
Zeros of Polynomial Functions
Problem 5
Textbook Question
Determine whether each statement is true or false. If false, explain why. A polynomial function having degree 6 and only real coefficients may have no real zeros.
Verified step by step guidance1
Recall the Fundamental Theorem of Algebra, which states that a polynomial of degree \(n\) has exactly \(n\) roots (zeros) in the complex number system, counting multiplicities.
Since the polynomial has degree 6, it must have exactly 6 roots in total, but these roots can be real or complex.
Because the polynomial has only real coefficients, any non-real complex roots must occur in conjugate pairs. This means complex roots come in pairs like \(a + bi\) and \(a - bi\).
If the polynomial had no real zeros, then all 6 roots would be complex and must come in conjugate pairs. Since 6 is even, it is possible to have 3 pairs of complex conjugate roots and no real roots.
Therefore, it is possible for a degree 6 polynomial with real coefficients to have no real zeros, making the statement true.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Polynomial Degree and Zeros
The degree of a polynomial indicates the highest power of the variable and determines the maximum number of zeros (roots) the polynomial can have. A polynomial of degree 6 can have up to 6 zeros, counting multiplicities and including complex zeros.
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Real and Complex Zeros
Polynomials with real coefficients may have zeros that are real or complex. Complex zeros occur in conjugate pairs, meaning if a + bi is a zero, then a - bi is also a zero. This ensures the polynomial's coefficients remain real.
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Introduction to Complex Numbers
Fundamental Theorem of Algebra
This theorem states that every non-constant polynomial has at least one complex root. For polynomials with real coefficients, all roots (real or complex) sum to the degree of the polynomial, but it is possible for a polynomial to have no real roots if all zeros are complex conjugates.
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