Recursive formula for sequence 1, -2, 3, -4, 5

[Twistlock]

Homework Statement

I need to find the recursive and explicit formulas for the sequence 1,-2, 3, -4, 5

Homework Equations

Recursive Rule: Fn= Fn-1 + Fn-2
Explicit Rule: position of terms F1, F2, F3,...

The Attempt at a Solution

I have figured out explicit because its ((-1)^n+1)n

Recursive rule i am having trouble with because its around something like -(Fn-1 +1) or close to that

 

[JSuarez]

Let a(n) be nth term. You should be able to say what a(1) is. Now manipulate the expression for a(n+1) until you have a right side that depends of a(n), a(n-1), etc.

 

[lanedance]

the sign of the added one will change depdneding on whether n is odd or even