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.
