Do you have to plug in numbers to make a sequence that is greater than 2?
2 or greater
a. The formula is an = an-1 - 3....so a2 = a2-1 - 3 = a1 - 3
Notice GM that we are just subtacting 3 from the previous term to get the next....and the first term is 7...so
7, 4, 1 , -2
This is arithmetic
b. The formula is bn = 2bn-1 - 1 .....so b2 = 2b(2-1) - 1 = 2b1 - 1
We are taking twice the previous term and subtracting 1 to get the next term and the first term is 2
So we have
2, 3, 5, 9
This is neither
c. The formula is cn = 10cn-1 ... so.....c2 = 10 c(2 - 1) = 10c1
So....we are just taking 10 times the previous term to h=get the next
So 3, 30, 300, 3000
geometric
d. A little tricky.....
We have
dn = n * dn-1 ..... first term is 1
Second term...n = 2
d2 = 2 * dn-1 = 2 * d(2 - 1) = 2 * d1 = 2 * 1 = 2
d3 = 3* d2 = 3 * 2 = 6
d4 = 4 * d3 = 4 * 6 = 24
So we have
1, 2, 6 , 24
neither......no common difference or common ratio