Complex Numbers And Quadratic Equations question 386

Question: If $ n $ is a positive integer, then $ {{( \frac{1+i}{1-i} )}^{4n+1}} $ =

Options:

A) 1

B) - 1

C) $ i $

D) $ -i $

Show Answer

Answer:

Correct Answer: C

Solution:

Since $ \frac{1+i}{1-i}=\frac{(1+i)(1+i)}{(1-i)(1+i)}=i $ Therefore $ {{( \frac{1+i}{1-i} )}^{4n+1}}={i^{4n+1}}=ii^{4n}=i(\because i^{4n}=1) $