[中學] 求級數和
各位板大 小弟不才，想請問這個級數怎麼算(或有通解嗎?)
c為常數，0<c<1，
r跟N為很大的正整數，求
N
sum {(c^k)/k}
k=r
有啥技巧嗎?比如拆開，或轉成積分？還是有啥近似的式子？
感激不盡！
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推
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