If f(n+1)=f(n) + 1/3 and f(1)=0 what is f(79)? I know this is super easy but I can't think of how to start it.

Question

If f(n+1)=f(n) + 1/3 and f(1)=0 what is f(79)?  I know this is super easy but I can't think of how to start it.

hartnn · Answer

f(n+1) = f(n) +1/3

is equivalent to f(n+1) = f(1) + n*(1/3)

do you need to derive this result ?

hartnn · Answer

there ?

anonymous · Answer

Nevermind.  Lol that wasn't it anyway.  I ended up figuring it out.

Solution to my problem:
n=1 then f(n)=0, f(2)=f(1)+1/3

f(1)=0
f(2)=1/3
f(3)=2/3
f(4)=1 or 3/3  

By this time you can see the pattern and we can see that for f(n)=(n-1)*1/3

So for f(79) we can just plug in and see that its 26.

anonymous · Answer

Like I said, easy.  Just a brainfart.  But thanks for trying to help.

hartnn · Answer

yeah i got the same equation algebraically, not by noticing the 'pattern'