1. **State the problem:** We are given a polynomial $$P(x) = x^3 - 4x^2 - x + 4$$ and told that $$(x-1)$$ is a factor. We need to express $$P(x)$$ as a product of factors.
2. **Recall the factor theorem:** If $$(x - a)$$ is a factor of $$P(x)$$, then $$P(a) = 0$$.
3. **Verify that $$(x-1)$$ is a factor:** Substitute $$x=1$$ into $$P(x)$$:
$$P(1) = 1^3 - 4(1)^2 - 1 + 4 = 1 - 4 - 1 + 4 = 0$$
Since $$P(1) = 0$$, $$(x-1)$$ is indeed a factor.
4. **Divide $$P(x)$$ by $$(x-1)$$ to find the other factor:** Use polynomial division or synthetic division.
Synthetic division setup:
Coefficients: 1 (for $$x^3$$), -4 (for $$x^2$$), -1 (for $$x$$), 4 (constant)
Divide by root $$x=1$$:
Carry down 1.
Multiply 1 * 1 = 1, add to -4 = -3.
Multiply 1 * -3 = -3, add to -1 = -4.
Multiply 1 * -4 = -4, add to 4 = 0 (remainder).
So the quotient is $$x^2 - 3x - 4$$.
5. **Factor the quadratic $$x^2 - 3x - 4$$:**
Find two numbers that multiply to $$-4$$ and add to $$-3$$: these are $$-4$$ and $$1$$.
So,
$$x^2 - 3x - 4 = (x - 4)(x + 1)$$.
6. **Write the full factorization:**
$$P(x) = (x - 1)(x - 4)(x + 1)$$.
7. **Check the options:** The correct factorization is $$(x - 1)(x - 4)(x + 1)$$.
**Final answer:** $$(x - 1)(x - 4)(x + 1)$$
Factor Polynomial 8274B0
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