Maths

Class 11

Maths · Class 11 · Chapter 8

Sequences and Series

10 lessons 89 min 2 simulations

This chapter treats a sequence as an ordered list of numbers, given by a formula for the nth term, by a recurrence or by a description, and a series as the sum of its terms, written with sigma notation. Most of the chapter is on geometric progressions: the common ratio, the nth term arⁿ⁻¹, the sum of n terms, problems on growth and decay, the geometric mean and inserting numbers between two given ones, and finally the inequality between the arithmetic and geometric means, A ≥ G.

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What the exam asks

For JEE Main, G.P. questions test the nth term, the sum of n terms, finding a and r from two conditions, three terms taken as a/r, a, ar, and A ≥ G used to find a least or greatest value. Arithmetic progressions from earlier classes are used alongside. JEE also expects the sum of an infinite G.P. with |r| < 1 and the sums of n, n² and n³, which the rationalised text names in its introduction but does not develop, so they need practice from other material.

Lessons

10 lessons · 89 min