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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
1
−
a
r
\sum_{r=2}^{n} \frac{1}{1-a_r}
∑
r
=
2
n
1
−
a
r
1
, is a.
n
4
\frac{n}{4}
4
n
b.
n
(
n
−
1
)
2
\frac{n(n-1)}{2}
2
n
(
n
−
1
)
c.
n
−
1
2
\frac{n-1}{2}
2
n
−
1
d. None of these
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