Solution
Let f(x) = (x – a)3 + (x – b)3 + (x – c)3.
Then f'(x) = 3{(x – a)2 + (x – b)2 + (x –c)2}
clearly , f'(x) > 0 for all x.
so, f'(x) = 0 has no real roots.
Hence, f(x) = 0 has two imaginary and one real root
Let the given equation be:
$f(x) = (x - a)^3 + (x - b)^3 + (x - c)^3 = 0$
Differentiate $f(x)$ with respect to $x$
$f'(x) = 3(x - a)^2 + 3(x - b)^2 + 3(x - c)^2$
$f'(x) = 3\left[(x - a)^2 + (x - b)^2 + (x - c)^2\right]$
Step 2: Analyze the Nature of $f'(x)$
Since the square of any real number is non-negative:
$(x - a)^2 \ge 0, \quad (x - b)^2 \ge 0, \quad (x - c)^2 \ge 0 \quad \text{for all } x \in \mathbb{R}$
If $a, b, c$ are not all equal, the sum of these three non-negative squares cannot simultaneously be zero for any real $x$:
$f'(x) > 0 \quad \text{for all } x \in \mathbb{R}$
If $a = b = c$, $f'(x) \ge 0$ (vanishing only at the single point $x = a$).
In both cases, $f(x)$ is a **strictly increasing function** on $\mathbb{R}$.
Conclusion:
1. As a cubic polynomial with real coefficients, $f(x) \to -\infty$ as $x \to -\infty$, and $f(x) \to +\infty$ as $x \to +\infty$.
2. Because $f(x)$ is strictly increasing, it can cross the x-axis **at most once**.
Therefore, the equation has **exactly one real root** and **two imaginary (complex conjugate) roots**.