The sum of the first seven terms of an arithmetic progression is equal to the sum of…
MATHEMATICS · Subjective · A Level · Mathematics · Sequences and series · Sequences and series
Problem
The sum of the first seven terms of an arithmetic progression is equal to the sum of the next seven terms and each of these sums is 175.
(i) Prove that the 8th term is 25.
(ii) Hence find the first term and the common difference of the progression.
(iii) Using your answers to part (ii), obtain the sum of the first 28 terms.