Question

F(n+1) = f(n) -2n if f(1) =18 what is f(5)

Answer 1

f(2) = f(1+1) = f(1) - 2*1= 16
f(3) = f(2+1) = f(2) - 2*2 = 12
and so on:
f(4) = 6
f(5) = -2