MATHEMATICS · Multi-part · A Level · Mathematics · Sequences and series · Sequences and series
Problem
In an arithmetic progression, the 4th term and the 8th term are in the ratio 5 : 9. The 6th term of the same progression is 41.
(i) Form two equations in the first term a and the common difference d using the given information.
(ii) Solve the equations to find a and d.
(iii) Determine the 20th term.
(iv) Find the sum of the first 25 terms of the progression.