A geometric series is a+ar+ar2+…a + ar + ar^2 + \dotsa+ar+ar2+…
Prove that the sum of the first n n\,n terms of the series is
Sn=a(1−rn)1−r S_n = \frac{a(1-r^n)}{1-r} Sn=1−ra(1−rn)178 exam-style questions on Edexcel A Level Maths Sequences and Series, covering 3.1 Arithmetic Sequences, 3.2 Arithmetic Series, 3.3 Geometric Sequences, 3.4 Geometric Series, 3.5 Sum to Infinity, 3.6 Sigma Notation, 3.7 Recurrence Relations, and 3.8 Modelling with Series. Each one has a worked solution and a mark scheme showing where the marks go.