Arithmetic sequences and seriesEdexcel A-Level Maths: Mind map

Exam questions on Arithmetic sequences and series

1. An arithmetic sequence has first term $7$ and common difference $4$.
   Find the smallest value of $n$ for which the $n$th term is greater than $200$.2 marks
2. The sum of the first $10$ terms of an arithmetic series is $185$ and the sum of the first $20$ terms is $670$.
   Find the sum of the $11$th to the $20$th terms inclusive.2 marks
3. An arithmetic series has first term $a$ and common difference $d$.
   Prove that the sum of the first $n$ terms is $S_n=\frac{n}{2}\left[2a+(n-1)d\right]$.3 marks