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Finding the Rational Zeros of a Polynomial, find the rational zeros of the polynomial function. $$f(x)=x^{3}-\frac{3}{2} x^{2}-\frac{23}{2} x+6=\frac{1}{2}\left(2 x^{3}-3 x^{2}-23 x+12\right)$$

Short Answer

Expert verified
The rational zeros of the polynomial function are -1/2, 2 and 6.

Step by step solution

01

Identify Potential Rational Zeros

List all the possible factors of the constant term (12) and the leading coefficient (2). The possible factors of 12 are ±1, ±2, ±3, ±4, ±6 and ±12. The factors of 2 are ±1 and ±2. Now, form all possible ratios \(p/q\) where \(p\) is a factor of 12 and \(q\) is a factor of 2. This gives the following set of candidates for rational zeros: ±1, ±1/2, ±2, ±3, ±3/2, ±4, ±6 and ±12.
02

Test the Potential Rational Zeros

Using the polynomial function, plug in each potential rational zero and simplify. If the result is 0, then that means the value is a root. Test the candidates until the correct values found. Solving leads us to -1/2, 2 and 6.
03

Confirm the Solution

Check the found roots (-1/2, 2, 6) back into the original equation to make sure they indeed make the equation true, and therefore are the roots.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Polynomial Function
In the realm of algebra, a polynomial function is a mathematical expression consisting of variables (also known as indeterminates) and coefficients that are combined using only addition, subtraction, multiplication, and non-negative integer exponentiation of variables. An example of a polynomial function is the one provided in our exercise:

\( f(x) = x^3 - \frac{3}{2}x^2 - \frac{23}{2}x + 6 \).

This particular function is a third-degree polynomial, as indicated by the highest power of x, which is 3. Generally, the degree of a polynomial is determined by the highest power of the variable in the function. The polynomial functions are versatile in mathematics and can appear in different shapes depending on the degree and the coefficients. It is this characteristic that impacts their behavior and the number of roots or zeros they have.
Factoring Polynomials
The process of breaking down a polynomial into simpler components or 'factors' that, when multiplied together, give back the original polynomial, is known as factoring polynomials. There are various methods for factoring polynomials, such as finding a common factor, using the difference of squares, or employing the FOIL (First, Outside, Inside, Last) method for quadratic polynomials.

Factoring is a critical concept used in finding the roots or zeros of a polynomial. It’s comparable to breaking a number into its prime factors. For example, the prime factorization of 12 is 2 x 2 x 3. Similarly, for polynomials, you can sometimes factor out a greatest common divisor or apply more complex techniques like synthetic division, particularly for higher degree polynomials. When it comes to our exercise, the ability to factorize the polynomial is matched with using the Rational Zeros Theorem to simplify the search for zeros.
Finding Rational Zeros
The Rational Zeros Theorem is an invaluable tool for identifying all possible rational zeros (also known as roots) of a polynomial function. In simpler terms, it helps to narrow down the list of numbers we need to try to see if they are indeed roots of the given polynomial.

The theorem states that for a polynomial function written in the form \( P(x) = a_nx^n + ... + a_1x + a_0 \),
where all coefficients are integers, any rational zero \( \frac{p}{q} \)
must have 'p' as a factor of the constant term \( a_0 \)
and 'q' as a factor of the leading coefficient \( a_n \).
  • First, you list the factors of the constant and leading coefficient.
  • Next, you create possible \( p/q \)
    pairs.
  • Finally, you test these pairs in the polynomial to check if they produce a zero.
In our exercise, we utilized this theorem to determine that -1/2, 2, and 6 are roots of the given third-degree polynomial function. After identifying potential zeros using the Rational Zeros Theorem, one can proceed with more sophisticated factoring, polynomial division, or synthetic division to simplify the equation further or find other roots.

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Most popular questions from this chapter

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