# Thread: Recursive!!! Am I doing this right??

1. ## Recursive!!! Am I doing this right??

Q: Find f(1), f(2), f(3), f(4), and f(5) if f(n) is defined recursively by f(0) = 3
and for n = 0, 1, 2, …
a.) f(n + 1) = -2f(n)
__________________________________________________ _______________
a.)
f(n + 1) = -2f(n)
f(0 + 1) = -2f(0)
f(1) = -2(3)
f(1) = - 6

f(n + 1) = -2f(n)
f(1 + 1) = -2f(1)
f(2) = -2(-6)
f(2) = 12

f(n + 1) = -2f(n)
f(2 + 1) = -2f(2)
f(3) = -2(12)
f(3) = -24

f(n + 1) = -2f(n)
f(3 + 1) = -2f(3)
f(4) = -2(-24)
f(4) = 48

f(n + 1) = -2f(n)
f(4 + 1) = -2f(4)
f(5) = -2(48)
f(5) = -96

2. Originally Posted by Grillakis
Q: Find f(1), f(2), f(3), f(4), and f(5) if f(n) is defined recursively by f(0) = 3
and for n = 0, 1, 2, …
a.) f(n + 1) = -2f(n)
__________________________________________________ _______________
a.)
f(n + 1) = -2f(n)
f(0 + 1) = -2f(0)
f(1) = -2(3)
f(1) = - 6

f(n + 1) = -2f(n)
f(1 + 1) = -2f(1)
f(2) = -2(-6)
f(2) = 12

f(n + 1) = -2f(n)
f(2 + 1) = -2f(2)
f(3) = -2(12)
f(3) = -24

f(n + 1) = -2f(n)
f(3 + 1) = -2f(3)
f(4) = -2(-24)
f(4) = 48

f(n + 1) = -2f(n)
f(4 + 1) = -2f(4)
f(5) = -2(48)
f(5) = -96
Looks OK.

3. Originally Posted by mr fantastic
Looks OK.
just wanted to know if im on the right track because I have b, c, and d with different function. Thanks