1.

The recursive rule for a sequence is shown.

an=an−1+9

a1=21

What is the explicit rule for this sequence?

an=12n−9

an=9n−12

an=9n+12

an=12n+9

2.

The explicit rule for a sequence is

an=17−5n.

What is the recursive rule for the sequence?

an=an−1+12, a1=5

an=an−1−5, a1=12

an=an−1+5, a1=12

an=an−1−12, a1=5

Thanks so much for all your help.

Guest Apr 15, 2018

#1**+2 **

First one :

The difference between successive terms is 9 and the first term is 21

So we must have that

a_{1} = 12n + 9 ⇒ a_{1} = 12 (1) + 9 = 21

So...the last answer is correct

Second one

a_{n} = 17 - 5n

The difference between successive terms is - 5 and the first term is 12

So we have

a_{n} = a_{n-1} - 5

a_{1} = 12

Second answer

CPhill Apr 15, 2018