(i)[3]
Determine the sum to infinity of progression $R$.
(ii)[3]
Given that the first term of $R$ is $4$, determine the sum of the first three terms of $R$.
Mathematics 9709 · AS & A Level · Series
Series — practice question
The first three terms of an arithmetic progression are formed by the sums to infinity of three geometric progressions, $P$, $Q$ and $R$, in that order. Progression $P$ has terms $2, 1, \frac{1}{2}, \frac{1}{4}, \ldots$. Progression $Q$ has terms $3, 1, \frac{1}{3}, \frac{1}{9}, \ldots$.
Worked solution & mark scheme
This 6-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Application of the sum to infinity formula $S_p = \dfrac{a}{1-r}$ to either series.” …
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