(m) Evaluate ∑ k = 1 ∞ ( ( 1 5 ) k + ( 1 2 ) k − 1 ) {\textstyle \sum _{k=1}^{\infty }\left(\left({\frac {1}{5}}\right)^{k}+\left({\frac {1}{2}}\right)^{k-1}\right)} .
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