Complex Numbers And Quadratic Equations question 255
Question: The roots of the equation $ x^{4}-1=0 $ , are [MP PET 1986]
Options:
A) $ 1,1,i,-i $
B) $ 1,-1,i,-i $
C) $ 1,-1,\omega ,{{\omega }^{2}} $
D) None of these
Show Answer
Answer:
Correct Answer: B
Solution:
Given equation $ x^{4}-1=0 $
Þ $ (x^{2}-1)(x^{2}+1)=0 $
Þ $ x^{2}=1 $ and $ x^{2}=-1 $
Þ $ x=\pm 1,\pm i $
BETA
