SOLUTION: How can the sum of this sequence, -5, -2, 1, 4, 7 be represented?

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Question 459240: How can the sum of this sequence, -5, -2, 1, 4, 7 be represented?
Answer by J2R2R(94) About Me  (Show Source):
You can put this solution on YOUR website!
First of all you can see it increases by 3 each time, so the nth term is of the form 3n + c

The first term is - 5, so 3(1) + c = - 5 giving c = -8

Thus the formula for the nth term An = 3n - 8

n = 1; A1 = 3 - 8 = - 5
n = 2; A2 = 6 - 8 = - 2
n = 3; A3 = 9 - 8 = 1
n = 4; A4 = 12 - 8 = 4
n = 5; A5 = 15 - 8 = 7