Number System - Part 3 of 5

Number System (Part 3 of 5)

 

PROGRESSION

This topic covers the concepts of AP and GP and their formulas to solve the questions related to the Progression !!

A  succession of numbers formed  and  arranged  in  a  definite  order  according  to  certain definite rule, is called a progression.

1. Arithmetic  Progression  (A.P.) 

If  each term  of  a  progression  differs  from  its preceding  term  by  a  constant,  then  such  a  progression  is  called  an  arithmetical progression. This constant difference is called the common difference of the A.P.
An A.P. with first term a and common difference d is given by a, (a + d), (a + 2d), (a + 3d) …
The nth term of this A.P. is given by Tn =a (n - 1) d.
The sum of n terms of this A.P. Sn = n/2 [2a + (n - 1) d] = n/2   (first term + last term)

2. Geometrical Progression  (G.P.) 

A progression of numbers in which every term bears a constant ratio with its preceding term, is called a geometrical progression. The constant ratio is called the common ratio of the G.P. A G.P. with first term a and common ratio r is... a, ar, ar2
In this G.P. Tn = arn-1 and  Sn = a(1-rn) / (1-r)

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