Question

Is the sequence {a_n}={0.4,1.6,6.4,25.6,...} arithmetic, geometric, or neither? If arithmetic, identify the common difference, d. If the sequence is geometric, identify the common ratio, r.

a) arithmetic; d=1.2
b) arithmetic; d=4
c) geometric; r=1.2
d) geometric; r=4
e) neither

Answer 1

d) geometric; r = 4

Explanation:

Answer 2

d) geometric; r = 4

Explanation:

Differences of adjacent terms are not constant (they are 1.2, 4.8, 19.2, ...), so the sequence is NOT ARITHMETIC.

Ratios of adjacent terms are constant (they are 1.6/0.4 = 6.4/1.6 = 25.6/6.4 = 4), so the sequence is geometric with a common ratio of 4.