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Determine the value of the positive integer $n$.
Mathematics 9709 · AS & A Level · Series
Series — practice question
An arithmetic progression has first term 61 and second term 57. The sum of the first $n$ terms is $n$.
Worked solution & mark scheme
This 4-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Application of the arithmetic progression sum formula $\frac{n}{2}[2a+(n-1)d]$ with $a=61$, $d=-4$” …
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