Answer:
[tex]a_{n}[/tex] = 4n + 5
Step-by-step explanation:
The n th term of an arithmetic sequence is
[tex]a_{n}[/tex] = a₁ + (n - 1)d
where a₁ is the first term and d the common difference
Here a₁ = 9 and d = a₂ - a₁ = 13 - 9 = 4 , thus
[tex]a_{n}[/tex] = 9 + 4(n - 1) = 9 + 4n - 4 = 4n + 5
