Question

Ecursive formula f (n + 1) = f(n) – 2. If f(1) = 18, what is f(5)?

Answer 1

`f(5) = 10`

Explanation:

`f(n+1) = f(n)-2\\\\f(1) = 18\\\\f(1+1) =f(2)= f(1) -2 = 18 -2 = 16~~~~~~~~~~~~;[n=1]\\\\f(2+1) =f(3) = f(2) -2 = 16-2 = 14~~~~~~~~~~~~;[n=2]\\\\f(3+1) = f(4)= f(3) -2 = 14-2 = 12~~~~~~~~~~~~~;[n=3]\\\\f(4+1) = f(5) = f(4) -2 = 12 -2 = 10~~~~~~~~~~~~~~;[n=4]\\\\\text{Hence,}~ f(5) =10.`