Which of the following formulas may be used to generate the sequence, 12, 19, 26, 33, 40, …? a. an = 7n + 5 b. an = n + 7 c. an = 7n + 12 d. an = 2n - 5

We first note that the difference of each 2 consecutive terms is 7:

19-12=7
26-19=7
33-26=7
40-7=7

Let represent the n'th term of the sequence, 

then clearly:






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Thus,

A

The best estimate would be about 1 foot