1. **State the problem:** Factor the polynomial $$P(x) = 3x^4 + x^3 - 14x^2 - 4x + 8$$ completely.
2. **List possible rational zeros:** By the Rational Root Theorem, possible zeros are of the form $$\pm \frac{p}{q}$$ where $$p$$ divides the constant term 8 and $$q$$ divides the leading coefficient 3.
Possible values of $$p$$: 1, 2, 4, 8
Possible values of $$q$$: 1, 3
Thus, possible zeros are:
$$\pm 1, \pm 2, \pm 4, \pm 8, \pm \frac{1}{3}, \pm \frac{2}{3}, \pm \frac{4}{3}, \pm \frac{8}{3}$$
3. **Test zeros using synthetic division:** Start testing with integer candidates.
Test $$x=1$$:
$$P(1) = 3(1)^4 + 1^3 - 14(1)^2 - 4(1) + 8 = 3 + 1 - 14 - 4 + 8 = -6 \neq 0$$
Test $$x=-1$$:
$$P(-1) = 3(-1)^4 + (-1)^3 - 14(-1)^2 - 4(-1) + 8 = 3 - 1 - 14 + 4 + 8 = 0$$
So, $$x = -1$$ is a root.
4. **Divide $$P(x)$$ by $$x + 1$$ using synthetic division:**
Coefficients: 3, 1, -14, -4, 8
Synthetic division setup:
-1 | 3 1 -14 -4 8
| -3 2 12 -8
-------------------
3 -2 -12 8 0
Quotient polynomial:
$$3x^3 - 2x^2 - 12x + 8$$
5. **Factor the cubic $$3x^3 - 2x^2 - 12x + 8$$:**
Try rational roots again for the cubic.
Possible zeros: $$\pm 1, \pm 2, \pm 4, \pm \frac{1}{3}, \pm \frac{2}{3}, \pm \frac{4}{3}$$
Test $$x=2$$:
$$3(2)^3 - 2(2)^2 - 12(2) + 8 = 24 - 8 - 24 + 8 = 0$$
So, $$x=2$$ is a root.
6. **Divide cubic by $$x - 2$$:**
Coefficients: 3, -2, -12, 8
Synthetic division:
2 | 3 -2 -12 8
| 6 8 -8
----------------
3 4 -4 0
Quotient polynomial:
$$3x^2 + 4x - 4$$
7. **Factor quadratic $$3x^2 + 4x - 4$$:**
Use quadratic formula:
$$x = \frac{-4 \pm \sqrt{4^2 - 4 \cdot 3 \cdot (-4)}}{2 \cdot 3} = \frac{-4 \pm \sqrt{16 + 48}}{6} = \frac{-4 \pm \sqrt{64}}{6} = \frac{-4 \pm 8}{6}$$
Roots:
$$x = \frac{-4 + 8}{6} = \frac{4}{6} = \frac{2}{3}$$
$$x = \frac{-4 - 8}{6} = \frac{-12}{6} = -2$$
8. **Write full factorization:**
$$P(x) = (x + 1)(x - 2)(3x^2 + 4x - 4) = (x + 1)(x - 2)(3x - 2)(x + 2)$$
**Final answer:**
$$\boxed{(x + 1)(x - 2)(3x - 2)(x + 2)}$$
Polynomial Factorization A6E247
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