f(1) = 2 and f(2) = 5, f(n) = f(1) + f(2) + f(n - 1), for n 2.

f(5) = ______
please help!!!!!!!!!!!

Question

f(1) = 2 and f(2) = 5, f(n) = f(1) + f(2) + f(n - 1), for n > 2.

f(5) = ______
please help!!!!!!!!!!!

loser66 · Answer

$$f(\color{red}{n})= f(1)+f(2) +f(\color{red}{n}-1)$$
so that
$$f(\color{red}{5})= f(1)+f(2) +f(\color{red}{5}-1)\=f(\color{red}{5})= f(1)+f(2) +f(4)$$ 
you have f(1) =2, f(2)= 5
all you need is f(4) . so find f(4) by exactly the way you find f(5). You will have f(3) there. :)
So?? repeat the process to get f(3), plug back to take f(4) , again, plug back to get f(5)
Practice to get the concept. :) 
Although it is a little bit long, but there is no other way to find out. You have to handle it by yourself.