Question 11 - A-Level Maths

Exam Board	Edexcel
Module	Paper 2 (Paper 2)
Session	Specimen
Topic	Arithmetic Sequences and Series

The second, third and fourth terms of an arithmetic sequence are \(2 k , 5 k - 10\) and \(7 k - 14\) respectively, where \(k\) is a constant.

Show that the sum of the first \(n\) terms of the sequence is a square number.