Complex Numbers And Quadratic Equations question 287

Question: Find the value of $ {{(1+2\omega +{{\omega }^{2}})}^{3n}}-{{(1+\omega +2{{\omega }^{2}})}^{3n}}= $ [UPSEAT 2002]

Options:

A) 0

B) 1

C) $ \omega $

D) $ {{\omega }^{2}} $

Show Answer

Answer:

Correct Answer: A

Solution:

$ {{[(1+\omega +{{\omega }^{2}})+\omega ]}^{3n}}-{{[(1+\omega +{{\omega }^{2}})+{{\omega }^{2}}]}^{3n}} $ $ ={{\omega }^{3n}}-{{({{\omega }^{2}})}^{3n}} $ $ ={{({{\omega }^{3}})}^{n}}-{{({{\omega }^{3}})}^{2n}} $ $ =1^{n}-1^{2n}=0 $ .