Math Problem Statement

Factor f(x) = 3x^3 + 28x^2 - x - 90, given that x = -2 is a zero.

Solution

I can see the math problem from your screenshot, which asks to factor f(x)=3x3+28x2x90f(x) = 3x^3 + 28x^2 - x - 90 given that x=2x = -2 is a zero.

To solve this, we can use synthetic division since we know that x=2x = -2 is a root. Let's go through the steps:

Step 1: Set up synthetic division

We use x+2x + 2 as the divisor because the given zero is x=2x = -2.

The coefficients of the polynomial f(x)=3x3+28x2x90f(x) = 3x^3 + 28x^2 - x - 90 are: [3,28,1,90][3, 28, -1, -90].

Step 2: Perform synthetic division

We divide the polynomial by x+2x + 2:

  1. Bring down the first coefficient, 33.
  2. Multiply 33 by 2-2, giving 6-6, and add to 2828, resulting in 2222.
  3. Multiply 2222 by 2-2, giving 44-44, and add to 1-1, resulting in 45-45.
  4. Multiply 45-45 by 2-2, giving 9090, and add to 90-90, resulting in 00 (remainder).

The quotient is 3x2+22x453x^2 + 22x - 45, with a remainder of 0, confirming that x=2x = -2 is a factor.

Step 3: Factor the quadratic

Now, we factor the quadratic 3x2+22x453x^2 + 22x - 45.

We need two numbers that multiply to 3×45=1353 \times -45 = -135 and add to 2222. These numbers are 2727 and 5-5.

So, rewrite the middle term: 3x2+27x5x453x^2 + 27x - 5x - 45 Factor by grouping: 3x(x+9)5(x+9)3x(x + 9) - 5(x + 9) Factor out the common binomial: (3x5)(x+9)(3x - 5)(x + 9)

Final Answer:

The complete factorization of f(x)f(x) is: f(x)=(x+2)(3x5)(x+9)f(x) = (x + 2)(3x - 5)(x + 9)

Would you like further details on any step? Here are five related questions to explore further:

  1. How do you perform synthetic division for higher-degree polynomials?
  2. What is the significance of the remainder in synthetic division?
  3. How can we use the Rational Root Theorem to find potential roots?
  4. What are the methods for factoring quadratic expressions?
  5. How can you verify your factorization of a polynomial?

Tip: When factoring polynomials, always check your work by multiplying the factors back together to ensure you recover the original polynomial.

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Math Problem Analysis

Mathematical Concepts

Synthetic Division
Polynomial Factorization
Quadratic Equations

Formulas

Synthetic division steps
Factorization of quadratic equations

Theorems

Remainder Theorem
Zero of a polynomial

Suitable Grade Level

Grade 11-12 or early college (Algebra II or Pre-Calculus)