Determine the different possibilities for the numbers of positive, negative, and nonreal complex zeros of each function. See Example 7. ƒ(x)=11x5-x3+7x-5
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4. Polynomial Functions
Zeros of Polynomial Functions
Problem 111
Textbook Question
Find all complex zeros of each polynomial function. Give exact values. List multiple zeros as necessary.* ƒ(x)=x4-6x3+7x2
Verified step by step guidance1
Start by writing down the polynomial function: \(f(x) = x^4 - 6x^3 + 7x^2\).
Factor out the greatest common factor (GCF) from all terms. Since each term contains \(x^2\), factor it out: \(f(x) = x^2(x^2 - 6x + 7)\).
Set the factored form equal to zero to find the zeros: \(x^2(x^2 - 6x + 7) = 0\). This implies either \(x^2 = 0\) or \(x^2 - 6x + 7 = 0\).
Solve the first equation \(x^2 = 0\) to find the zeros from this factor. Then, solve the quadratic equation \(x^2 - 6x + 7 = 0\) using the quadratic formula: \(x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}\), where \(a=1\), \(b=-6\), and \(c=7\).
Simplify the solutions from the quadratic formula to find the exact complex zeros. Combine these with the zeros from \(x^2=0\) to list all complex zeros of the polynomial.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Polynomial Zeros
Polynomial zeros are the values of x for which the polynomial equals zero. Finding zeros involves solving the equation f(x) = 0. These zeros can be real or complex numbers and represent the roots of the polynomial function.
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Factoring Polynomials
Factoring is the process of expressing a polynomial as a product of simpler polynomials. It helps in finding zeros by setting each factor equal to zero. Techniques include factoring out common terms, grouping, or using special formulas like difference of squares.
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Complex Numbers and the Fundamental Theorem of Algebra
The Fundamental Theorem of Algebra states that a polynomial of degree n has exactly n roots in the complex number system, counting multiplicities. Complex numbers include real and imaginary parts, allowing solutions beyond real zeros when factoring over the reals is not possible.
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