Math Problem Statement

Write the polynomial x^3 + x^2 - 8x - 12 as a product of linear factors.

Solution

To write the polynomial x3+x28x12x^3 + x^2 - 8x - 12 as a product of linear factors, we need to factor it fully. Let's proceed step by step:

Step 1: Look for possible rational roots.

Using the Rational Root Theorem, the possible rational roots are factors of the constant term (-12) divided by the factors of the leading coefficient (1), so the possible roots are:

±1,±2,±3,±4,±6,±12\pm 1, \pm 2, \pm 3, \pm 4, \pm 6, \pm 12

Step 2: Test the possible roots using synthetic division or substitution.

Let’s try x=2x = 2:

f(2)=23+228(2)12=8+41612=16f(2) = 2^3 + 2^2 - 8(2) - 12 = 8 + 4 - 16 - 12 = -16

x=2x = 2 is not a root.

Now, try x=2x = -2:

f(2)=(2)3+(2)28(2)12=8+4+1612=0f(-2) = (-2)^3 + (-2)^2 - 8(-2) - 12 = -8 + 4 + 16 - 12 = 0

So, x=2x = -2 is a root.

Step 3: Perform synthetic division.

We will now divide x3+x28x12x^3 + x^2 - 8x - 12 by x+2x + 2 using synthetic division:

-2 & 1 & 1 & -8 & -12 \\ & & -2 & 2 & 12 \\ \hline & 1 & -1 & -6 & 0 \\ \end{array}$$ The quotient is $$x^2 - x - 6$$. ### Step 4: Factor the quadratic $$x^2 - x - 6$$. We need to factor $$x^2 - x - 6$$. We find two numbers that multiply to -6 and add to -1. These numbers are -3 and 2, so: $$x^2 - x - 6 = (x - 3)(x + 2)$$ ### Step 5: Write the polynomial as a product of linear factors. We now have the full factorization: $$x^3 + x^2 - 8x - 12 = (x + 2)(x - 3)(x + 2)$$ Alternatively, this can be written as: $$(x + 2)^2(x - 3)$$ This is the polynomial expressed as a product of linear factors. Would you like further details or clarifications? --- Here are some related questions you may want to explore: 1. How does the Rational Root Theorem help in factoring polynomials? 2. Can all cubic polynomials be factored into linear factors? 3. What happens when there are complex roots in the factorization process? 4. How does synthetic division differ from polynomial long division? 5. How can you check if your factorization is correct? **Tip**: Always check your factorization by multiplying the factors back to ensure you get the original polynomial!

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Math Problem Analysis

Mathematical Concepts

Polynomial Factoring
Synthetic Division
Rational Root Theorem

Formulas

f(x) = a(x - r1)(x - r2)...(x - rn)

Theorems

Rational Root Theorem

Suitable Grade Level

Grades 10-12