If $\omega$ is a non-real cube root of unity, then the value of $\dfrac{a + b\omega + c\omega^2}{b + c\omega + a\omega^2} + \dfrac{a + b\omega + c\omega^2}{c + a\omega + b\omega^2}$ is equal to:
Step-by-Step Solution
Key Concept: Properties of cube roots of unity
Step 1: Establish the properties of the cube root of unity.
Since $\omega$ is a non-real cube root of unity, we have:
$$\omega^3 = 1 \quad \text{and} \quad 1 + \omega + \omega^2 = 0$$
These are fundamental properties that will be used throughout the solution.
Step 2: Simplify the first fraction by recognizing a cyclic pattern.
Let $p = a + b\omega + c\omega^2$.
Multiply $p$ by $\omega^2$:
$$\omega^2 p = a\omega^2 + b\omega^3 + c\omega^4$$
Since $\omega^3 = 1$, we have $\omega^4 = \omega$, so:
$$\omega^2 p = a\omega^2 + b(1) + c\omega = b + c\omega + a\omega^2$$
This means the denominator of the first fraction equals $\omega^2 p$. Therefore:
$$\frac{a + b\omega + c\omega^2}{b + c\omega + a\omega^2} = \frac{p}{\omega^2 p} = \frac{1}{\omega^2} = \omega$$
(using the fact that $\omega^{-2} = \omega$ since $\omega^3 = 1$)
Step 3: Simplify the second fraction using the same cyclic pattern.
Multiply $p$ by $\omega$:
$$\omega p = a\omega + b\omega^2 + c\omega^3$$
Since $\omega^3 = 1$:
$$\omega p = a\omega + b\omega^2 + c = c + a\omega + b\omega^2$$
This means the denominator of the second fraction equals $\omega p$. Therefore:
$$\frac{a + b\omega + c\omega^2}{c + a\omega + b\omega^2} = \frac{p}{\omega p} = \frac{1}{\omega} = \omega^2$$
(using the fact that $\omega^{-1} = \omega^2$ since $\omega^3 = 1$)
Step 4: Add the two fractions to find the final answer.
$$\frac{a + b\omega + c\omega^2}{b + c\omega + a\omega^2} + \frac{a + b\omega + c\omega^2}{c + a\omega + b\omega^2} = \omega + \omega^2$$
Using the fundamental property $1 + \omega + \omega^2 = 0$, we get:
$$\omega + \omega^2 = -1$$
**Final Answer:** The value of the given expression is $\boxed{-1}$, which corresponds to **Option 4**.
Correct Answer: 3