Question

If f(1) = 4 and f(n) = f(n − 1) + 5 then find the value of f(5).

Answer 1

25

Explanation:

f(5)=5(5-1)+5

f(5)=5(4)+5

f(5)=20+5

f(5)=25

Answer 2

f(5) = 24

Explanation:

f(1) = 4

f(n) = f(n − 1) + 5

Let n = 2

f(2) = f(2 − 1) + 5 = 4+5 = 9

Let n = 3

f(3) = f(3 − 1) + 5 = f(2)+5 = 9+5 = 14

Let n = 4

f(4) = f(4 − 1) + 5 = f(3)+5 = 14+5 = 19

Let n = 5

f(5) = f(5 − 1) + 5 = f(4)+5 = 19+5 = 24