Neco 2020 Mathematics Question 9

Practice essay / theory question 9 from the 2020 Neco Mathematics examination. This question covers Sequences and Series .

Neco 2020 Mathematics Essay / Theory

Topic: Sequences and Series

Question 9 NECO • 2020 • MATHEMATICS • essay

The sum of the first \(n\) terms of an arithmetic progression (AP) is given by \(S_n = 3n^{2}+2n\).

Question Parts

( a )

Find the 10th term of the AP and state its common difference \(d\).

( b )

A geometric progression (GP) is formed whose first term equals the 10th term of the AP and whose common ratio \(r\) is given by \(r = \dfrac{d}{a_{10}}\). Find the sum of the first 20 terms of this GP, giving your answer to the nearest integer.

( c )

State, with a brief justification, whether the sum of the first 20 terms of the GP will increase, decrease or remain the same if the common difference of the original AP were doubled while all other conditions stayed unchanged.

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About This Question

This is Neco 2020 Mathematics Question 9. It is one of the essay questions from the 2020 Neco Mathematics examination.

The question covers Sequences and Series .

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