Question

Find a formula for the nth term in thisarithmetic sequence:a1 = 9,a2 = 13, a3 = 17, a4 = 21, ...an:?

Answer 1

Given:

$a_1=9,a_2=13,a_3=17,a_4=21$

To find:

The nth term formula.

Explanation:

The nth term formula is,

$a_n=a+(n-1)d$

The first term a = 9.

The common difference is,

$\begin{gathered} d=13-9 \\ =4 \end{gathered}$

So, the nth term formula for the sequence is,

$\begin{gathered} a_n=9+(n-1)(4) \\ =9+4n-4 \\ =5+4n \end{gathered}$

Therefore, the nth term formula is,

$a_n=5+4n$

Final answer:

The nth term formula is,

$a_n=5+4n$