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 AQA A Level Maths 1.7 D: Sequences and series with exam-style questions for A Level Maths. 267 questions covering 1.7.1 Binomial expansion, 1.7.2 Types of sequence (A-level only), 1.7.3 Sigma notation (A-level only), 1.7.4 Arithmetic sequences and series (A-level only), 1.7.5 Geometric sequences and series (A-level only), and 1.7.6 Sequences and series in modelling (A-level only), matched to the AQA A Level Maths (7357) 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.
