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