Math Problem Statement

Explain

Find all the zeros of f(x) = x^3 + x^2 - 14x - 24 if one of the zeros is 4.

Solution

The problem given is:

f(x)=x3+x214x24f(x) = x^3 + x^2 - 14x - 24

You are asked to find all the zeros of f(x)f(x), knowing that one of the zeros is x=4x = 4.

Step 1: Use Synthetic Division or Polynomial Division

Since x=4x = 4 is a zero of the polynomial, we can divide the polynomial f(x)f(x) by (x4)(x - 4).

Using synthetic division to divide f(x)f(x) by (x4)(x - 4):

  1. Write down the coefficients of the polynomial: 1,1,14,241, 1, -14, -24.
  2. Perform synthetic division using 44:
   4 |   1    1    -14   -24
      |        4    20    24
      ----------------------
        1    5     6     0

The quotient is x2+5x+6x^2 + 5x + 6, and the remainder is 0 (which confirms x=4x = 4 is indeed a root).

Step 2: Factor the Quotient

Now, we need to solve x2+5x+6=0x^2 + 5x + 6 = 0.

Factorizing the quadratic: x2+5x+6=(x+2)(x+3)x^2 + 5x + 6 = (x + 2)(x + 3)

Step 3: Solve for the Remaining Zeros

From the factorization, we get: x+2=0orx+3=0x + 2 = 0 \quad \text{or} \quad x + 3 = 0 So, x=2x = -2 and x=3x = -3.

Final Answer:

The zeros of f(x)=x3+x214x24f(x) = x^3 + x^2 - 14x - 24 are: x=4,x=2,x=3x = 4, \quad x = -2, \quad x = -3

Would you like further details on synthetic division or how the quadratic was factored?

Here are 5 related questions to deepen your understanding:

  1. How do you perform synthetic division for higher-degree polynomials?
  2. What are the steps to factor a quadratic polynomial?
  3. Can you use the Rational Root Theorem to find potential zeros of a cubic polynomial?
  4. How does synthetic division confirm that a number is a zero of a polynomial?
  5. How would the approach change if a complex root was involved?

Tip: Always check your work by plugging the found roots back into the original polynomial to verify that they make the equation equal to zero.

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Math Problem Analysis

Mathematical Concepts

Polynomials
Synthetic Division
Quadratic Factorization

Formulas

Synthetic division method
Factoring quadratics: (x + a)(x + b) = 0

Theorems

Factor Theorem
Quadratic Factorization

Suitable Grade Level

Grades 10-12