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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

Respuesta :

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 [tex]\displaystyle{ a_n[/tex] represent the n'th term of the sequence, 

then clearly:

[tex]\displaystyle{ a_1=7\cdot1+5=12[/tex]

[tex]\displaystyle{ a_1=7\cdot2+5=19[/tex]

[tex]\displaystyle{ a_1=7\cdot3+5=26[/tex]
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Thus, [tex]\displaystyle{ a_n=7n+5[/tex]


Answer: A

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