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Mathematics
Mathematics
Problem
The value of
∑
r
=
2
∞
tan
−
1
(
1
r
2
−
5
r
+
7
)
\sum_{r=2}^{\infty} \tan^{-1}\left(\frac{1}{r^2-5r+7}\right)
∑
r
=
2
∞
tan
−
1
(
r
2
−
5
r
+
7
1
)
, is a.
π
4
\frac{\pi}{4}
4
π
b.
π
2
\frac{\pi}{2}
2
π
c.
3
π
4
\frac{3\pi}{4}
4
3
π
d.
5
π
4
\frac{5\pi}{4}
4
5
π
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