Question

A sequence is defined by the formula f(n+1)=f(n)-3. If f(4)=22, what is f(1)?​

Answer 1

f(1) = 31

Explanation:

since f(n+1) -f(n) = -3

this sequence is arithmetic when the common diff is d= -3

the general term is :

f(n) = f(1) +(n-1)d

put n = 4

f(4) = f(1)+(4-1)(-3)

22 = f(1) - 9

f(1) = 31