if (x - 1), (x + 1) and (x - 2) are factors of the polynomial \(ax^3 + bx^2 + cx - 1\), find a, b, c in that order.
The correct answer is A. -1/2, 1., 1/2
Let's solve this problem step by step. We are given that the polynomial \(ax^3 + bx^2 + cx - 1\) has factors `(x - 1)`, `(x + 1)` and `(x - 2)`. We need to find the values of `a`, `b`, and `c`.
Since `(x - 1)`, `(x + 1)` and `(x - 2)` are factors of the polynomial, we can write the polynomial as: \(ax^3 + bx^2 + cx - 1 = k(x - 1)(x + 1)(x - 2)\), where `k` is a constant.
Expanding the right side of this equation, we get: \(k(x - 1)(x + 1)(x - 2) = k(x^2 - 1)(x - 2) = k(x^3 - x^2 - 2x + 2)\).
Comparing the coefficients of the left and right sides of this equation, we find that:
- `a = k`
- `b = -k`
- `c = -2k`
- `-1 = 2k`
Solving for `k`, we find that `k = -1/2`. Substituting this value into the equations for `a`, `b`, and `c`, we get:
- `a = k = -1/2`
- `b = -k = 1`
- `c = -2k = 1`
Therefore, the values of `a`, `b`, and `c` are **-1/2**, **1**, and **1/2**, respectively.
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