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26 votes
26 votes
Find the 80th term of the following arithmetic sequence. 4, 12, 20, 28

User Vsemozhebuty
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1 Answer

17 votes
17 votes

First of all, the formula to find the n-term of an arithmetic sequence is:


\begin{gathered} a_n=a_1+(n-1).d;\text{ where} \\ a_n\text{ term that we need find} \\ a_1\text{ first term = 4} \\ n\text{ number of term = 80} \\ d\text{ = common diference = 8} \end{gathered}

Now, replacing with the knowing values:


\begin{gathered} a_n=4+(80-1)\cdot8 \\ a_n=4+79\cdot8=4+632=636 \\ a_(80)=636 \end{gathered}

Your answer is the 80th term of that arithmetic sequence is 636.

User Sinisa
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