
Mark M. answered 12/14/22
Tutor
5.0
(278)
Mathematics Teacher - NCLB Highly Qualified
The common difference is -7
an = 12.6 + (n -1)(-7)

David E.
asked 12/14/22It's been a while since I've done arithmetic and geometric formulas. I'm positive that it's arithmetic, but I don't know whether to put parentheses or just replace the addition sign with a subtraction sign.
Mark M. answered 12/14/22
Mathematics Teacher - NCLB Highly Qualified
The common difference is -7
an = 12.6 + (n -1)(-7)
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David W.
Since the student said, "It's been a while ...," why not also write a(n) = a(1) + (n-1)(d) ??12/14/22