Answer:
[tex]\large\begin{cases}a_1=5 \\a_n=a_{(n-1)}-4\end{cases}[/tex]
Step-by-step explanation:
Recursive formula allows us to find the value of a specific term based on the previous term.
Explicit formula allows us to find the value of a specific term based on its position.
Given explicit formula: [tex]a(n)=5+(n-1)(-4)[/tex]
[tex]\implies a(1)=5+(1-1)(-4)=5[/tex]
[tex]\implies a(2)=5+(2-1)(-4)=1[/tex]
[tex]\implies a(3)=5+(3-1)(-4)=-3[/tex]
[tex]\implies a(4)=5+(4-1)(-4)=-7[/tex]
From inspection of the sequence, we can see that to get the next term, we need to subtract 4 from the previous term.
[tex]5 \underset{-4}{\longrightarrow} 1 \underset{-4}{\longrightarrow} -3 \underset{-4}{\longrightarrow} -7[/tex]
Therefore, the recursive formula is:
[tex]a_n=a_{(n-1)}-4[/tex]
For a recursive formula, we also need to give the value for [tex]a_1[/tex] .
Therefore, the final recursive formula for the explicit formula is:
[tex]\large\begin{cases}a_1=5 \\a_n=a_{(n-1)}-4\end{cases}[/tex]
