We have the sequence:
121, 97, 73, 49, 25.
First, we have to look if there is a common difference between the terms of the sequence:
[tex]\begin{gathered} 97-121=-24 \\ 73-97=-24 \\ 49-73=-24 \\ 25-49=-24 \end{gathered}[/tex]We have a common difference of d=-24, so we can write the sequence in recursive form as:
[tex]a_n=a_{n-1}-24[/tex]