SEQUENCE - the nth term of a sequence

ACADEMY"The reason many students fail mathematics is because they first fired the salvo of hatred and by the time the subject retaliated, they found it difficult to understand" E.A Adeboye
pH.D in applied Mathematics.





SEQUENCE 


A sequence is a succession of number stated in a definite order. Each of its member is formed and guided according to a definite rule. To solve a given sequence, you'll have to  think of a well define rule that satisfy the sequence.




Worked examples:

(1).       1, 3, 5, 7, 9.         (Rule: adding two to the preceding term)

1+2 =3, 
3+2 =5

(11).   2, 5, 8, 11,......(Rule: 3n - 1)

solo:   3(1) - 1 = 
             3 - 1 = 2,
3(2) - 1
= 6 - 1 = 5

 4,. 11, 30, 67,... ( Rule: n³+ 3)

1³ + 3 = 4,
2³ + 3 = 11

Hope you understand!




Solving For The ₙth Term Of A Sequence



The number occuring at the  place of a sequence is called the ₙth term of a sequence, we substitute for the number of  'n' in the given nth term formula. That is, a formula will be given and you'll substitute the number of  'n'  given in the formula.  A sequence do come with a define formula.



Worked examples


The ₙth term of a sequence is given as 3n² - 8n + 4. What is the 5th term?

solution:
The nth term Tₙ = 3n² - 8n+ 4 (the formula given)

Tₙ = 3(5)² - 8x5 + 4..  (substitute)
= 3x 25 - 8x5 + 4
75 - 40 +4 = 39




Example 11
if  the sum of the first nth term of a sequence given by n² ⁻ 2n + 4. Find the sum of the T₁ and T₅

solution 
Tₙ  = Sn - Sn - 1 ( the nth term of sequence as related to sum of a sequence)

Tₙ = n² - 2n +4 (the given formula )




Sₙ =  n² - 2n + 4

Sₙ ₋₁ = ( n - 1)² - 2(n -) + 4
= n² - 4n + 7 
hence, to gether will be

Tₙ = Sₙ - Sₙ ₋ ₁
Tₙ = n² - 2n +4 - ( n² -  4n + 7)
Tₙ = n² - 2n + 4 - n² +  4n - 7
= 2n - 3


Tₙ = 2n - 3
T₁ = 2( 1)
      2 - 1 = 1


T₅ = 2( 5) - 3
         10 - 3 = 7



Example 111

If for all integer nth  term a sequence is given as 

Uₙ ₊₁ = 1/3 ( Uₙ + 1) and U₁ = 1/3,find U₃

solution
Uₙ₊₁ = 1/3 (Uₙ + 1) ; U₁ = 1/3

U₂ = U₁ ₊₁ = 1/3 (U₁ +1) = 1/3 (1/3 +1) =1/3 x 4/3 = 4/9


U₃ = U₂ ₊₁ = 1/3 ( U₃ +1) = 1/3 (4/9 +1 ) = 1/3 x 13/9 = 13/27


Attempt this and send your answer in the comment section or through any of our social platform:


The nth term of a sequence is Tₙ = 5( n - 1)² . Evaluate T₄ ₋ T₆


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