# Déjà vu

Calculus Level 3

$\dfrac{a-b}{a}+\dfrac{1}{2} \left(\dfrac{a-b}{a} \right)^2+\dfrac{1}{3} \left(\dfrac{a-b}{a} \right)^3+ \ldots$

If $$0 < b < a$$, the value of the above series is?

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