I can’t figure this out

Write a function that matches the description. a cosine function has a maximum of 5 and a minimum value of -5. f (r) =

Any is very appreciated! (picture is provided below)not sure how to do this at all won't lie

1c) the number 131 is a term in the sequence defined by the explicit rule f(n)=5n-4. which term in the sequence is 131? 2a) write the first four terms of the function f(n)=n^2-1 2b) what is the 10th term of the sequence defined by the explicit rule f(n)=n^2-1 2c) the number 224 is a term in the sequence defined by the explicit rule f(n)=n^2-1. which term in the sequence is 224?