Question

Match Term Definition
128, 32, 8, 2, ... A) Geometric, common ratio is 3
1, 3, 9, 27, ... B) Geometric, common ratio is 0.25
5, 10, 15, 20, ... C) Arithmetic, common difference is -3
20, 17, 14, 11, ... D) Arithmetic, common difference is 5

Answer 1

@Nurali

Answer 2

ok for a geometric, you can take the 2nd term divided by the first term and that will be your common ratio, if all a_n+1 / a_n has the same common ratio that will tell you it is in fact a geometric sequence

Answer 3

waits what is it @Nurali @billj5

Answer 4

for an arithmetic, you can take the absolute value of 2nd term minus the first term and that will be your common difference, if all absolute value of a_n+1 - a_n has the same common difference that will tell you it is in fact an arithmetic sequence

Answer 5

so what is the correct way @nurali @billj5

Answer 6

what do u think @texaschic101

Answer 7

if the number is multiplied by a certain number to get to the next number, then it is an geometric sequence. If the number is added/subtracted to find the next number, it is an arithmetic sequence.
128,32,8,2 ..
32/128 = 0.25
check..
128 * 0.25 = 32
32 * 0.25 = 8
the common ratio is 0.25 (geometric)

1,3,9,27
3/1 = 3
check..
1 * 3 = 3
3 * 3 = 9
9 * 3 = 27
the common ratio is 3 (geometric)

5,10,15,20
10 - 5 = 5
15 - 10 = 5
20 - 15 = 5
common difference is 5 (arithmetic)

20,17,14,11
20 - 3 = 17
17 - 3 = 14
14 - 3 = 11
common difference is -3 (arithmetic)