If (√(3) + i)ⁿ = (√(3) - i)ⁿ, find the smallest positive integer value of n — JEE Mathematics
If $(\sqrt{3} + i)^{n} = (\sqrt{3} - i)^{n}$, find the smallest positive integer value of $n$.
1 Answer
Rewrite both sides in polar form:
$$\sqrt{3} + i = 2\left(\cos\frac{\pi}{6} + i\sin\frac{\pi}{6}\right) = 2e^{i\pi/6}$$
$$\sqrt{3} - i = 2\left(\cos\frac{\pi}{6} - i\sin\frac{\pi}{6}\right) = 2e^{-i\pi/6}$$
Substitute these into the equation:
$$(2e^{i\pi/6})^n = (2e^{-i\pi/6})^n$$
$$2^n e^{in\pi/6} = 2^n e^{-in\pi/6}$$
Divide by $2^n e^{-in\pi/6}$:
$$e^{i 2n\pi/6} = 1 \implies e^{in\pi/3} = 1$$
For $e^{in\pi/3} = 1$, the exponent must be a multiple of $2\pi i$:
$$\frac{n\pi}{3} = 2k\pi \implies n = 6k \quad (k \in \mathbb{Z})$$
The smallest positive integer $n$ occurs when $k = 1$:
$$n = 6$$
Answer: 6