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Joint Entrance Examination
Mathematics
Complex Numbers
Question 342
Question 342 of 455
Medium
MCQ
If
ω
(
≠
1
)
\omega(\ne1)
ω
(
=
1
)
is a cube root of unity, and
(
1
+
ω
)
7
=
A
+
B
ω
(1+\omega)^7=A+B\omega
(
1
+
ω
)
7
=
A
+
B
ω
, then
(
A
,
B
)
(A,B)
(
A
,
B
)
equals
A
(1,1)
B
(1,0)
C
(-1,1)
D
(0,1)
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Official solution
\[{\left( {1 + \omega } \right)^7} = A + B\omega ;\,\,\,\,{\left( { - {\omega ^2}} \right)^7} = A + B\omega \] \[ - {\omega ^2} = A + B\omega ;\,\,\,\,\,\,\,\,\,\,1 + \omega = A + B\omega \] \[ \Rightarrow A = 1,B = 1.\]
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