Math Problem Statement

Use the Rational Zero Test to list the possible rational zeros of f. Verify that the zeros of f shown on the graph are contained in the list. (Enter your answers as a comma-separated list.) f(x) = x cubed − 9x squared − 9x + 81

Solution

To list the possible rational zeros of the polynomial function f(x)=x39x29x+81f(x) = x^3 - 9x^2 - 9x + 81 using the Rational Zero Test, we follow these steps:

Rational Zero Test:

The possible rational zeros of a polynomial are given by the following formula:

Possible Rational Zeros=Factors of the constant termFactors of the leading coefficient\text{Possible Rational Zeros} = \frac{\text{Factors of the constant term}}{\text{Factors of the leading coefficient}}

  1. Constant term: The constant term in f(x)f(x) is 8181.
  2. Leading coefficient: The leading coefficient of f(x)f(x) is the coefficient of x3x^3, which is 11.

Step 1: List the factors of the constant term 8181.

The factors of 8181 are:

±1,±3,±9,±27,±81\pm 1, \pm 3, \pm 9, \pm 27, \pm 81

Step 2: List the factors of the leading coefficient 11.

The factors of 11 are:

±1\pm 1

Step 3: Use the Rational Zero Test formula.

Now, using the Rational Zero Test, the possible rational zeros are all the factors of 8181 divided by the factors of 11, which are:

±1,±3,±9,±27,±81\pm 1, \pm 3, \pm 9, \pm 27, \pm 81

Thus, the possible rational zeros are:

±1,±3,±9,±27,±81\boxed{\pm 1, \pm 3, \pm 9, \pm 27, \pm 81}

Verifying the Zeros from the Graph:

If you have a graph of the function f(x)=x39x29x+81f(x) = x^3 - 9x^2 - 9x + 81, check if any of these values (e.g., 1,3,9,27,811, 3, 9, 27, 81) are zeros of the function, meaning where the graph crosses or touches the x-axis. If any of the zeros match, they are confirmed to be part of the possible rational zeros list.

Would you like help with graphing or further exploration on how to find the actual zeros?

Related Questions:

  1. How do we use synthetic division to confirm the zeros?
  2. What happens when a zero is repeated (multiplicity)?
  3. Can you explain the difference between rational and irrational zeros?
  4. How does the Rational Zero Test relate to the Factor Theorem?
  5. How do we simplify factoring cubics?

Tip:

The Rational Zero Test provides possible rational zeros, but you'll need to test each one or use synthetic division to find the actual zeros.

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Math Problem Analysis

Mathematical Concepts

Polynomials
Rational Zero Test
Algebra

Formulas

Possible Rational Zeros = (Factors of the constant term) / (Factors of the leading coefficient)

Theorems

Rational Zero Theorem

Suitable Grade Level

Grades 10-12