Answer:f(n)= -6.5n +14.5f(1)= 8, f(n+1) = f(n) - 6.5Step-by-step explanation:the arithmetic sequence 8, 1.5, –5, –11.5 . . . First term is 8Now we find difference between the terms1.5 - 8= -6.5-5-1.5= -6.5difference is -6.5The formula is f(n)= a1 + (n-1)dwhere a1 is the first term and d is the differencef(n)= 8 + (n-1)(-6.5)f(n)= 8 -6.5n+6.5f(n)= -6.5n +14.5To get recursive formula we use f(n+1) = f(n)+ differencef(1)= 8, f(n+1) = f(n) - 6.5