Mathematics 9709 · AS & A Level · Series

Series — practice question

The sum, $S_n$, of the first $n$ terms in an arithmetic progression is $S_n = n^2 + 4n$. The $k$th term of the progression exceeds $200$.

(main)[5]

Determine the least possible value of $k$.

Worked solution & mark scheme

This 5-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Applies $S_n$ and $S_{n+1}$ correctly” …