The first three terms of a geometric series are (2k+2)(2k+2)(2k+2), (k+4)(k+4)(k+4), and k k\,k respectively, where k k\,k is a positive constant.
Show that k2−6k−16=0k^2 - 6k - 16 = 0k2−6k−16=0.
Hence show that k=8k = 8k=8.
Find the common ratio.
Find the sum to infinity of the series.
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.