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 Edexcel A Level Maths 3.5 Sum to Infinity with exam-style questions for A Level Maths. 18 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.