Question

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

Answer 1

-19

Explanation:

f(1) = 1

Substitute f(1) = 1

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

= f(1) - 5

+ (1) - 5

f(2) = -4

Substitute f(2) = -4

f(3) = f(3-1) -5

= f(2) -5

= (-4) -5

f(3) = -9

Substitute f(3) = -9

f(4) = f(4-1) - 5

= f(3) -5

= (-9) -5

f(4) = -14

Substitute f(4) = -14

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

= f(4) -5

= (-14) -5

f(5) = -19

Common difference of -5

Arithmetic Sequence:

1,-4,-9,-14,-19

Answer 2

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

f(5) = -1