# Given the sequence 3, 6, 12, 24, ... calculate the 9th and the nth terms of the sequence .

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Student Comments

giorgiana1976 | Student

First, we'll from ratios from 2 consecutive terms of the given sequence:

6/3 = 2

12/6 = 2

24/12 = 2

We notice that all quotients are the same, so, the sequence is a geometric progression, whose first terms is a1 = 3 and the common ratio is r = 2.

We'll calculate a9:

a9 = a1*r^(9-1)

a9 = 3 * 2^8

a9 =3*256

**a9 = 768**

The standard formula for any term of a geometric progression is:

**an = a1*r^(n-1)**