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Write the term to term rule, position-to-term (nth term) and 20thterm of the sequence 3, -1 ,-5, -9, -13 ,....​

User KeelRisk
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1 Answer

8 votes

It's a arithmetic sequence

  • First term=a=3
  • common difference=d=-1-3=-4

Nth term rule:-


\\ \rm\Rrightarrow a_n=a+(n-1)d


\\ \rm\Rrightarrow a_n=3+(n-1)-4


\\ \rm\Rrightarrow a_n=3-4n+4


\\ \rm\Rrightarrow a_n=7-4n

20th term


\\ \rm\Rrightarrow a_(20)=7-80=-73

User Griable
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