Question

If f(1) = 10 and f(n) = -2f(n - 1) then find
the value of f(5).

Answer 1

f(1) = 10

f(2) = -2f(2 - 1) = -2f(1) = -2(10) = -20

f(3) = -2f(3 - 1) = -2f(2) = -2(-20) = 40

f(4) = -2f(4 - 1) = -2f(3) = -2(40) = -80

f(5) = -2f(5 - 1) = -2f(4) = -2(-80) = 160