The first three terms of a geometric series are (3k+8)(3k+8)(3k+8), (k+8)(k+8)(k+8), and k k\,k respectively, where k k\,k is a positive constant.
Show that k2−4k−32=0k^2 - 4k - 32 = 0k2−4k−32=0.
Hence show that k=8k = 8k=8.
Find the common ratio.
Find the sum to infinity of the series.
308 exam-style questions on AQA A Level Maths 1.7 D: Sequences and series, 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). Each one has a worked solution and a mark scheme showing where the marks go.