Question

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

Answer 1

Answer:

  an = 5n -7

Step-by-step 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.