Given:
[tex]a_1=-4[/tex] and [tex]a_n=a_{n-1}+9[/tex] where [tex]n\geq 2[/tex].
To find:
The explicit formula for the given recursive formula.
Solution:
We know that recursive formula of an AP is:
[tex]a_n=a_{n-1}+d[/tex]
Where, d is the common difference.
We have,
[tex]a_n=a_{n-1}+9[/tex]
Here, d=9.
The first term of the AP is [tex]a_1=-4[/tex].
The explicit formula for an AP is:
[tex]a_n=a_1+(n-1)d[/tex]
Substituting [tex]a_1=-4[/tex] and [tex]d=9[/tex], we get
[tex]a_n=-4+(n-1)9[/tex]
[tex]a_n=-4+9n-9[/tex]
[tex]a_n=-13+9n[/tex]
Therefore, the required explicit formula for the given sequence is [tex]a_n=-13+9n[/tex].
