Question

Find the explicit rule: 2, 6, 18, 54, 162

Answer 1

f(n) = 2 ×
`3^(n-1)`

Explanation:

In order to write an explicit rule for a geometric function, you need to know the common ratio; you can find the common ratio by dividing two consecutive terms:

6 ÷ 2 = 3, 18 ÷ 6 = 3, 54 ÷ 18 = 3, etc..

Now you know the common ratio is 3. At this point you can write your explicit function following the rule f(n) = [1st term] × [common ratio]^(n-1):

f(n) = 2 × 3^(n-1)

Answer 2

Multiply each number by 3.

2 (x 3) is 6. 6 x 3 is 18, 18 x 3 is 54, 54 x 3 is 162.

Hope this helps!