3. State the general version of the recursive formula.

72,54, 36, 18,0

a(1) = 72

a(n) = a (n-1) - 18

Step-by-step explanation:

This is a simple series of multiplication of 18 . If we divide all the numbers by 18 we get

72/18, 54/18, 36/18. 18/18, 0/18

4      , 3      , 2     , 1 ,       0

So we can see that the numbers are in  decreasing order as the multiples of 18.

in other words the first term is a= 72

from which we subtract 18 and get 54 and so on.

So the general rule would be

a(1) = 72

a(n) = a (n-1) - 18

Where n and (n-1 ) are subscripts. We are just subtracting 18 from the number to get the answer.

72-18= 54

54-18= 36

36-18= 18

18-18=0

.

step-by-step explanation:

a is the right answer