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AP EAMCET · Maths · Complex Number

If \(\mathrm{m}, \mathrm{n}\) are respectively the least positive and greatest negative integer values of \(k\) such that \(\left(\frac{1-i}{1+i}\right)^k=-i\), then \(m-n=\)

  1. A 4
  2. B 0
  3. C 6
  4. D 2
Verified Solution

Answer & Solution

Correct Answer

(A) 4

Step-by-step Solution

Detailed explanation

\(\text { Given }\left(\frac{1-i}{1+i}\right)^k=-i \Rightarrow\left\{\frac{(1-i)^2}{2}\right\}^k=-i \Rightarrow(-i)^k=-i\) If \(k=1\) (least positive integer) \(\Rightarrow(-i)^1=-i\) If \(k=-3\) (greatest negative integer) \(\Rightarrow(-i)^{-3}=-i\) So, \(m=1\) and…