Math Problem Statement

f(x)=9x4−12x3−38x2−20x−3f(x)=9x4-12x3-38x2-20x-3 has a zero of multiplicty 22 at x=−13x=-13. Find the remaining real zeros by using synthetic division with the known zero, then factor the polynomial completely.

Separate the remaining zeros with a comma. Use fractions, not decimals.

Remaining Zeros==

Factored Form: f(x)

Solution

We are given the polynomial f(x)=9x412x338x220x3f(x) = 9x^4 - 12x^3 - 38x^2 - 20x - 3 and we know that it has a zero of multiplicity 2 at x=13x = -\frac{1}{3}. To find the remaining real zeros, we can use synthetic division with x+13x + \frac{1}{3} as a divisor.

Step 1: Synthetic Division

We will perform synthetic division twice, because the zero has a multiplicity of 2, which means we must divide by x+13x + \frac{1}{3} two times.

  1. First Division:

    • The coefficients of the polynomial 9x412x338x220x39x^4 - 12x^3 - 38x^2 - 20x - 3 are: [9,12,38,20,3][9, -12, -38, -20, -3].
    • We divide by x+13x + \frac{1}{3} (which corresponds to using 13-\frac{1}{3} in synthetic division).
  2. Second Division:

    • Once we get the result from the first division, we repeat the process to divide again by x+13x + \frac{1}{3}.

Let's perform the division now.After performing synthetic division twice, the quotient we obtain is 9x218x279x^2 - 18x - 27, with a remainder of 0, indicating the division was successful.

Step 2: Factor the Quotient

Now, we need to factor 9x218x279x^2 - 18x - 27. First, factor out the common factor of 9:

9(x22x3)9(x^2 - 2x - 3)

Next, we factor x22x3x^2 - 2x - 3 by finding two numbers that multiply to -3 and add to -2. These numbers are -3 and 1:

9(x3)(x+1)9(x - 3)(x + 1)

Step 3: Factored Form of the Polynomial

The factored form of the original polynomial f(x)f(x) is:

f(x)=9(x+13)2(x3)(x+1)f(x) = 9(x + \frac{1}{3})^2(x - 3)(x + 1)

Step 4: Remaining Real Zeros

The remaining real zeros of the polynomial are x=3x = 3 and x=1x = -1.

Final Answer:

  • Remaining Zeros: 3,13, -1
  • Factored Form: f(x)=9(x+13)2(x3)(x+1)f(x) = 9(x + \frac{1}{3})^2(x - 3)(x + 1)

Do you need further details on the steps, or have any questions?

Here are some related questions to deepen your understanding:

  1. What is synthetic division, and how is it different from long division?
  2. How do you determine the multiplicity of a zero in a polynomial?
  3. Why is it important that the remainder is 0 when using synthetic division with a known zero?
  4. Can you factor a quadratic equation without factoring out a common term first?
  5. How does the factored form of a polynomial help in graphing its function?

Tip: When factoring polynomials, always check for common factors first to simplify your work.

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Math Problem Analysis

Mathematical Concepts

Polynomials
Synthetic Division
Factoring Polynomials
Multiplicity of Zeros

Formulas

Synthetic Division
Factoring Quadratics
General Polynomial Form

Theorems

Fundamental Theorem of Algebra

Suitable Grade Level

Grades 10-12