AQA Paper 1 2018 June — Question 9

Exam BoardAQA
ModulePaper 1 (Paper 1)
Year2018
SessionJune
TopicArithmetic Sequences and Series

9 An arithmetic sequence has first term \(a\) and common difference \(d\). The sum of the first 36 terms of the sequence is equal to the square of the sum of the first 6 terms. 9
  1. Show that \(4 a + 70 d = 4 a ^ { 2 } + 20 a d + 25 d ^ { 2 }\) 9
  2. Given that the sixth term of the sequence is 25 , find the smallest possible value of \(a\).