A sequence is defined by the formula [tex]$f(n+1)=f(n)-3$[/tex]. If [tex]$f(4)=22$[/tex], what is [tex][tex]$f(1)$[/tex][/tex]?

A. 10
B. 13
C. 31
D. 34



Answer :

Sure, let's solve for [tex]\( f(1) \)[/tex] using the provided sequence information.

We are given the sequence formula:
[tex]\[ f(n+1) = f(n) - 3 \][/tex]

And the specific value:
[tex]\[ f(4) = 22 \][/tex]

We need to find [tex]\( f(1) \)[/tex]. We'll work backward from [tex]\( f(4) \)[/tex].

First, let's find [tex]\( f(3) \)[/tex]:
[tex]\[ f(4) = f(3) - 3 \][/tex]
Substitute [tex]\( f(4) = 22 \)[/tex]:
[tex]\[ 22 = f(3) - 3 \][/tex]
Add 3 to both sides to solve for [tex]\( f(3) \)[/tex]:
[tex]\[ f(3) = 22 + 3 = 25 \][/tex]

Next, let's find [tex]\( f(2) \)[/tex]:
[tex]\[ f(3) = f(2) - 3 \][/tex]
Substitute [tex]\( f(3) = 25 \)[/tex]:
[tex]\[ 25 = f(2) - 3 \][/tex]
Add 3 to both sides to solve for [tex]\( f(2) \)[/tex]:
[tex]\[ f(2) = 25 + 3 = 28 \][/tex]

Finally, let's find [tex]\( f(1) \)[/tex]:
[tex]\[ f(2) = f(1) - 3 \][/tex]
Substitute [tex]\( f(2) = 28 \)[/tex]:
[tex]\[ 28 = f(1) - 3 \][/tex]
Add 3 to both sides to solve for [tex]\( f(1) \)[/tex]:
[tex]\[ f(1) = 28 + 3 = 31 \][/tex]

Thus, the value of [tex]\( f(1) \)[/tex] is:
[tex]\[ \boxed{31} \][/tex]