Tardigrade
Tardigrade - CET NEET JEE Exam App
Exams
Login
Signup
Tardigrade
Question
Mathematics
If x + (1/x) = 2 cos θ, then for any integer n, xn + (1/xn) =
Q. If
x
+
x
1
=
2
cos
θ
, then for any integer
n
,
x
n
+
x
n
1
=
2367
199
WBJEE
WBJEE 2011
Complex Numbers and Quadratic Equations
Report Error
A
2
cos
n
θ
64%
B
2
sin
n
θ
25%
C
2
i
cos
n
θ
9%
D
2
i
sin
n
θ
2%
Solution:
Let
x
=
cos
θ
+
i
sin
θ
Then,
x
1
=
cos
θ
−
i
sin
θ
∴
x
+
x
1
=
2
cos
θ
⇒
x
n
+
x
n
1
=
2
cos
n
θ