Question

The least positive integer n which will reduce ${\left(\frac{i-1}{i+1}\right)}^n$to a real number , is

• A. 2
• B. 3
• C. 4
• D. 5

Answer 1

The correct option is A

2

${(\frac{i-1}{i+1}\times \frac{i-1}{i-1})}^n={\left(\frac{-2i}{-2}\right)}^n=i^n$

Hence, to make the real number the least positive integar is 2.