Question
Question: If z is a nonreal root of \(\sqrt[7]{- 1}\) then z<sup>86</sup> + z<sup>175</sup> + z<sup>289</sup> ...
If z is a nonreal root of 7−1 then z86 + z175 + z289 is equal to-
A
0
B
–1
C
3
D
1
Answer
–1
Explanation
Solution
Sol. z7 = –1,
\ expression = (z7)12 . z2 + (z7)25 + (z7)41 . z2
= (–1)12 . z2 + (–1)25 + (–1)41 . z2
= z2 – 1 – z2 = –1.