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Mathematics
Problem
Equation
x
n
−
1
=
0
x^n - 1 = 0
x
n
−
1
=
0
,
n
>
1
n > 1
n
>
1
,
n
∈
N
n \in N
n
∈
N
, has roots
1
,
a
1
,
a
2
,
…
,
a
n
1, a_1, a_2, \dots, a_n
1
,
a
1
,
a
2
,
…
,
a
n
. The value of
∑
r
=
2
n
1
2
−
a
r
\sum_{r=2}^{n} \frac{1}{2-a_r}
∑
r
=
2
n
2
−
a
r
1
, is a.
2
n
−
1
(
n
−
2
)
+
1
2
n
−
1
\frac{2^{n-1}(n-2)+1}{2^n-1}
2
n
−
1
2
n
−
1
(
n
−
2
)
+
1
b.
2
n
(
n
−
2
)
+
1
2
n
−
1
\frac{2^n(n-2)+1}{2^n-1}
2
n
−
1
2
n
(
n
−
2
)
+
1
c.
2
n
−
1
(
n
−
1
)
−
1
2
n
−
1
\frac{2^{n-1}(n-1)-1}{2^n-1}
2
n
−
1
2
n
−
1
(
n
−
1
)
−
1
d. None of the above
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