Answer:
24a^9 b^11
Step-by-step explanation:

Answer:
Okay let me explain this to you so you understand
So what does f(n) mean?
Well F(n) is saying the function, of n.
Basically we need to make n be any random number.
Well what number do we choose?
In your question, it says n is greater than or equal than 2.
lets start with 2
f(n-1)+2
f(2-1)+2
1+2
3
f(2) is 3
lets do this 4 more times
that leaves us with the first 5 terms
these 5 terms are
3
4
5
6
7
The pattern is subtracting 9
B is the answer.
You can tell this by the series of translations. But you can also try in values to see which satisfy the equation.