In an arithmetic sequence, the rrr-th term is given by ur=u1+(r−1)du_r = u_1 + (r-1)dur=u1+(r−1)d, where u1 u_1\,u1 is the first term and d d\,d is the common difference.
Show that the sum of the first n n\,n terms of the corresponding arithmetic series is
Sn=n2(2u1+(n−1)d) S_n = \frac{n}{2}(2u_1 + (n-1)d) Sn=2n(2u1+(n−1)d)Practise Edexcel A Level Maths 3.2 Arithmetic Series with exam-style questions for A Level Maths. 38 questions, matched to the Edexcel A Level Maths (9MA0) specification and written in Paper 1, Paper 2 and Paper 3 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.