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Mathematics
Problem
Evaluate
∑
k
=
2
∞
5
2
1
−
k
\displaystyle \sum_{k=2}^{\infty} 5\,2^{1-k}
k
=
2
∑
∞
5
2
1
−
k
. a)
2.5
2.5
2.5
b)
5
5
5
c)
10
10
10
d)
5
3
\dfrac{5}{3}
3
5
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