SEQUENCE AND SERIES
*Understanding sequence and series
*Arithmetic progression
*Word problems on arithmetic progression
*Geometric progression
*Word problems on geometric progression
Understanding Sequence and series
Sequence: It is the set of numbers formed when numbers are listed in an order with a definite
rule. It can be in descending or ascending order.
E.g. 3,4,5,6,...............
5,10,15,20………
The number of terms to be found in any sequence is called the nth term. nth term is usually
demoted by Tn or Un. When first,second, third…….are to be found they are written as
T1,T2,T3………respectively.
Series: It is the addition of the terms of a sequence.
E.g. 3+4+5+6+...........
7+5+3+1+..........
Examples:
1; The nth term of a sequence is given by Tn=n(1-2n).
(a) Determine the first four terms of the sequence.
(b)Find the sum of the series of the first three terms.
(c)If Tn= -120, find the value of n
Solution
(a)Tn=n(1-2n)
When n=1
T1=1(1-2(1))
T1=1(1-2)
T1=1(-1)
T1= -1
When n=2
T2=2(1-2(2))
T2=2(1-4)
T2=2(-3)
T2= -6
When n=3
T3=3(1-2(3))
T3=3(1-6)
T3=3(-5)
T3= -15
When n=4
