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

User Filoche
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1 Answer

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Given:


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

To find:

The nth term formula.

Step-by-step 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
User Just A Learner
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