This all looks confusing and hard... Solve Please!

b.  Look at the y values for A   and we have  2, 5, 8, 11, 14, 17, 20

This is arithmetic.....common difference =3   and first term = 2

So....

an  = 2 + 3(n - 1)   =  3n - 1

c. Look at the y values for B and we have     1/2, 1, 2, 4, 8, 16

This is geometric.....common ratio  =1/(1/2)  =  2   and the first term = 1/2

So....

an  = (1/2)(2)^(n - 1)

d.  See c.....we have a common ratio.....this always indicates a geometric progression