Name __________________________________
Date ____________ Period ___________
Sequence HW
Are the sequences in Exercises 1-4 arithmetic? If so, identify the constant difference, d, and
write a recursive formula and an explicit formula for the nth term of the sequence.
1) 2, 7, 11, 14,…
2) 2, 7, 12, 17,…
3) 2, -5, -12, -19,…
4) 2, -5, -11, -16,…
Are the sequences in Exercises 5-8 geometric? If so, identify the constant ratio, and write a
recursive formula and an explicit formula for the nth term of the sequence.
5) 2, 6, 18, 54,…
1
1 1
2
4 8
7) 2, -1, , - , ,…
6) 2, 0.2, 0.02, 0.002,…
8) 2, 4, 8, 12,…
Are the sequences in Exercises 9-17 arithmetic, geometric, or neither? For the ones which are
arithmetic or geometric, identify the constant difference/ratio, and write a recursive formula and
an explicit formula for the nth term of the sequence.
9) 6, 9, 12, 15,…
10) 1, -1, 2, -2,…
11) -1, -1.1, -1.2, -1.3,…
12) 4, 12, 36, 108,…
1 1
1 1
13) 4, 2, 1, , ,…
14) 4, 1, , ,…
15) 4, 0.4, 0.04, 0.004,…
16) 2, -4, 8, -16,…
2 4
17) 1,
1
,
1.2
1
(1.2)2
,
4 8
1
(1.2)3
,…
18. During 2001, about 75 million barrels of oil a day were consumed worldwide. Over the
previous decade, consumption had been rising at 1.2% per year; assume that it continues to
increase at this rate.
a) Write the first four terms of the sequence an giving daily oil consumption n years after
2000; then write an explicit formula for the general term an.
b) In what year is consumption expected to exceed 100 million barrels per day?
c) Between 2000 and 2001, world oil consumption actually dropped by 0.2%, rather than
growing by 1.2%. If this trend continues, write the first four terms of an under this
assumption. What would oil usage be in the year you found in part (b)?