Is the sequence [an] ={1, 2.5, 4, 5.5, 1...] arithmetic? If so. identify the common difference. 0 A. yes, -1.5 O B. yes, 0.5 O C. yes, 1.5 O D. no 1 11 19 9 Write a recursive formula for the arithmetic sequence {a,} = 1 8. 8' 24' 24' 8 , ... O A. a ; an = an-1+ O B. a= -; an = an-1+ O C. a= =;an = -n+ O D. az n+Write an explicit formula for the arithmetic sequence {a,,} = {-2, 7, 16, 25, . ..) . O A. a, = 9n-7 O B. a, = 5x-7 O C. a = 11-13 O D. an = 9n-11If {a,) is an arithmetic sequence where a =-23 and the common difference is 6, find a79 . O A. 445 O B. 491 O C. 439 O D. 451In 1960, 11% of Americans completed four years or more of college. On average, this percentage has increased by 0.5% each year. Write a formula to describe the percentage of Americans completing four years or more of college. O A. a, = 0.5#+11 O B. a, = 0.5x+ 10.5 O C. a, =-0.5#+11 O D. a, = -0.5# +10.5