Complex Numbers And Quadratic Equations question 404

Question: If $ i^{2}=-1 $ , then sum $ i+i^{2}+i^{3}+… $ to 1000 terms is equal to [Kerala (Engg.) 2002]

Options:

A) 1

B) - 1

C) i

D) 0

Show Answer

Answer:

Correct Answer: D

Solution:

$ i+i^{2}+i^{3}+……. $ up to 1000 terms $ =\frac{i(1-i^{1000})}{1-i}= $ $ \frac{i(1-{{(i^{4})}^{250}})}{1-i} $ $ =\frac{i(1-1)}{1-i}=0 $ .