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Mathematics
Problem
The number
k
k
k
is such that
tan
{
arctan
(
2
)
+
arctan
(
20
k
)
}
=
k
\tan\{\arctan(2) + \arctan(20k)\} = k
tan
{
arctan
(
2
)
+
arctan
(
20
k
)}
=
k
. The sum of all possible values of
k
k
k
is a.
−
19
40
-\frac{19}{40}
−
40
19
b.
−
21
40
-\frac{21}{40}
−
40
21
c. 0 d.
1
5
\frac{1}{5}
5
1
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