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JEE Main 26 June 2022 Shift 2 Solved Paper
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© examsnet.com
Question : 23
Total: 90
If
z
2
+
z
+
1
=
0
,
z
∈
C
, then
|
15
∑
n
=
1
(
z
n
+
(
−
1
)
n
1
z
n
)
2
|
is equal to____
[26-Jun-2022-Shift-2]
Your Answer:
Validate
Solution:
👈: Video Solution
∵
z
2
+
z
+
1
=
0
⇒
ω
or
ω
2
∵
|
15
∑
n
=
1
(
z
n
+
(
−
1
)
n
1
z
n
)
2
|
=
|
15
∑
n
=
1
z
2
n
+
15
∑
n
=
1
z
−
2
n
+
2
⋅
15
∑
n
=
1
(
−
1
)
n
|
=
|
0
+
0
−
2
|
=
2
© examsnet.com
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