1. **State the problem:** Factor the cubic polynomial $x^3 + x^2 - 4x - 4$ using the factor theorem.
2. **Recall the factor theorem:** If $f(a) = 0$ for some number $a$, then $(x - a)$ is a factor of $f(x)$.
3. **Find possible rational roots:** Possible roots are factors of the constant term $-4$, i.e., $\pm1, \pm2, \pm4$.
4. **Test $x=1$:**
$$f(1) = 1^3 + 1^2 - 4(1) - 4 = 1 + 1 - 4 - 4 = -6 \neq 0$$
5. **Test $x=-1$:**
$$f(-1) = (-1)^3 + (-1)^2 - 4(-1) - 4 = -1 + 1 + 4 - 4 = 0$$
Since $f(-1) = 0$, $(x + 1)$ is a factor.
6. **Divide $f(x)$ by $(x + 1)$ using polynomial division:**
$$\frac{x^3 + x^2 - 4x - 4}{x + 1} = x^2 \cancel{+ x} - 2x \cancel{- 2}$$
7. **Write the quotient:**
$$x^2 - 2x - 4$$
8. **Factor the quadratic $x^2 - 2x - 4$ using the quadratic formula:**
$$x = \frac{2 \pm \sqrt{(-2)^2 - 4(1)(-4)}}{2(1)} = \frac{2 \pm \sqrt{4 + 16}}{2} = \frac{2 \pm \sqrt{20}}{2} = \frac{2 \pm 2\sqrt{5}}{2} = 1 \pm \sqrt{5}$$
9. **Final factorization:**
$$f(x) = (x + 1)(x - (1 + \sqrt{5}))(x - (1 - \sqrt{5}))$$
This is the complete factorization using the factor theorem and quadratic formula.
Factor Theorem C5Dcfc
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