Math Problem Statement

find all possible zeros P(x) = 2x4 − 8x3 + 4x2 + 8x − 6

Solution

We are tasked with finding all possible zeros of the polynomial function:

P(x)=2x48x3+4x2+8x6P(x) = 2x^4 - 8x^3 + 4x^2 + 8x - 6

Step 1: Apply the Rational Root Theorem

The Rational Root Theorem suggests that any rational solution, p/qp/q, must be a factor of the constant term (here, -6) divided by a factor of the leading coefficient (here, 2).

  • Factors of 6-6 (constant term): ±1,±2,±3,±6\pm 1, \pm 2, \pm 3, \pm 6
  • Factors of 22 (leading coefficient): ±1,±2\pm 1, \pm 2

Possible rational roots ( pq\frac{p}{q} ) are:

±1,±12,±2,±3,±32,±6\pm 1, \pm \frac{1}{2}, \pm 2, \pm 3, \pm \frac{3}{2}, \pm 6

Step 2: Test possible rational roots

We will substitute these values into P(x)P(x) to check which ones yield P(x)=0P(x) = 0.

Test x=1x = 1:

P(1)=2(1)48(1)3+4(1)2+8(1)6=28+4+86=0P(1) = 2(1)^4 - 8(1)^3 + 4(1)^2 + 8(1) - 6 = 2 - 8 + 4 + 8 - 6 = 0 So, x=1x = 1 is a root.

Step 3: Perform synthetic division

Now that x=1x = 1 is a root, we can use synthetic division to divide P(x)P(x) by (x1)(x - 1).

Synthetic division of P(x)P(x) by (x1)(x - 1) results in:

2x36x22x+62x^3 - 6x^2 - 2x + 6

Step 4: Factor the cubic polynomial

Now, factor 2x36x22x+62x^3 - 6x^2 - 2x + 6. We can take out a common factor of 2:

2(x33x2x+3)2(x^3 - 3x^2 - x + 3)

We can apply synthetic division again or use grouping to factor x33x2x+3x^3 - 3x^2 - x + 3. Testing for possible rational roots shows that x=3x = 3 is a root.

Step 5: Divide again

Synthetic division of x33x2x+3x^3 - 3x^2 - x + 3 by (x3)(x - 3) results in:

x21=(x1)(x+1)x^2 - 1 = (x - 1)(x + 1)

Step 6: Write the complete factorization

So, the factored form of P(x)P(x) is:

P(x)=2(x1)2(x+1)(x3)P(x) = 2(x - 1)^2(x + 1)(x - 3)

Step 7: Find the zeros

The zeros of the polynomial are:

x=1(with multiplicity 2),x=1,x=3x = 1 \quad (\text{with multiplicity 2}), \quad x = -1, \quad x = 3

Thus, the possible zeros are:

x=1,1,3x = 1, -1, 3

Would you like further explanation on any step or details? Here are five questions related to polynomial functions and factorization:

  1. How do you check if a number is a zero of a polynomial?
  2. What is the Rational Root Theorem and when do you use it?
  3. How does synthetic division help simplify polynomials?
  4. What is the significance of multiplicity in roots?
  5. How can grouping be used to factor cubic polynomials?

Tip: Always test simpler roots first (like ±1\pm 1) when applying the Rational Root Theorem for easier calculations.

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Math Problem Analysis

Mathematical Concepts

Polynomial Functions
Zeros of Polynomials
Synthetic Division
Factorization

Formulas

Rational Root Theorem: p/q, where p is a factor of the constant term and q is a factor of the leading coefficient
Synthetic division to simplify polynomials
Factoring polynomials

Theorems

Rational Root Theorem

Suitable Grade Level

Grades 10-12