Question
Question: If a is a complex number such that a<sup>2</sup> + a + 1 = 0, then a<sup>31</sup> is equal to...
If a is a complex number such that a2 + a + 1 = 0, then a31 is equal to
A
a
B
a2
C
0
D
1
Answer
a
Explanation
Solution
Sol. a = 2−1±1−4=2−1±3iŽ a =2−1+3i = w
a31 = w31 = w = a Q a = 2−1−3i = w2
a31 = (w2)31 = w62 = w2 = a