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criszerriny
- Junior | Next Rank: 30 Posts
- Posts: 19
- Joined: Mon Apr 20, 2009 2:25 pm
f(n)=f(n-1)-n and f(4)=10
f(4)=f(3)-4
10=f(3)-4
f(3)=14
f(3)=f(2)-3
17=f(2)
f(2)=17
f(3)=14
f(4)=10
Can you see the pattern here?
the difference between the two numbers is increasing by 1 each time as n increases.
The difference between f(5) and f(4) has to be 5, so
10-f(5)=5
f(5)=5
The difference between f(5) and f(6) has to be 6, so
5-f(6)=6
f(6)=-1
