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PLSSS HELP What is the formula for the following arithmetic sequence? -2, 3, 8, 13, ... an = -2n + 3 an = -2n + 7 an = 5n + 3 an = 5n - 7

1 Answer

5 votes

Answer:

an = 5n -7

Explanation:

Try the offered formulas with n= 1 and see which gives you the first term of the sequence.

an = -2n +3

-2(1) +3 = 1 . . . . not -2

an = -2n +7

-2(1) +7 = 5 . . . . not -2

an = 5n +3

5(1) +3 = 8 . . . . not -2

an = 5n -7

5(1) -7 = -2 . . . . this is the formula you want

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If you recognize the common difference of the sequence to be 5, then you can automatically eliminate any formulas that don't contain 5n.

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