SOLUTION: Find a formula for an for the arithmetic sequence. a1 = −1, a5 = 23

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Question 1178225: Find a formula for an for the arithmetic sequence.
a1 = −1, a5 = 23
Found 2 solutions by ikleyn, Boreal:
Answer by ikleyn(52816) About Me  (Show Source):
You can put this solution on YOUR website!
.

For introductory lessons on arithmetic progressions see
    - Arithmetic progressions
    - The proofs of the formulas for arithmetic progressions
    - Problems on arithmetic progressions
    - Word problems on arithmetic progressions
in this site.

Learn the subject from there (!)


Also,  you have this free of charge online textbook in ALGEBRA-II in this site
    - ALGEBRA-II - YOUR ONLINE TEXTBOOK.

The referred lessons are the part of this online textbook under the topic "Arithmetic progressions".


Save the link to this textbook together with its description

Free of charge online textbook in ALGEBRA-II
https://www.algebra.com/algebra/homework/complex/ALGEBRA-II-YOUR-ONLINE-TEXTBOOK.lesson

into your archive and use when it is needed.



Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
a1=-1 and a5=23, a difference in 24 with 4 terms between them, so difference between terms is 6
an=a1+d(n-1)
a5=-1+6(4)=23
an=-1+6(n-1)
-1,5,11,17,23