Recursive sequences

Question

if f(1)=2 and f(n)=-5f(n-1) then find the value of f(4)

Answer 1

f(1) = 2 and f(n) = -5*f(n - 1)

f(2) = -5*f(1) = (-5)(2) = -10

f(3) = -5*f(2) = (-5)(-10) = 50

f(4) = -5*f(3) = (-5)(50) = -250

This is a geometric sequence with the common ratio of -5.