NAME
DATE
7-8
PERIOD
Practice
Recursive Formulas
Find the first five terms of each sequence.
2. a 1 = -101, a n = a n - 1 + 38, n ≥ 2
25, 13, 1, -11, -23
3. a 1 = 3.3, a n = a n - 1 + 2.7, n ≥ 2
-101, -63, -25, 13, 51
4. a 1 = 7, a n = -3a n - 1 + 20, n ≥ 2
3.3, 6, 8.7, 11.4, 14.1
1
5. a 1 = 20, a n = −
a n - 1, n ≥ 2
5
7, -1, 23, -49, 167
2
2
1
6. a 1 = −
, an = −
an - 1 - −
,n≥2
3
3
9
8
26
2
2
−
, 0, - −
, -−
, -−
3
9
27
81
4 4
4
20, 4, −
, −, −
5 25 125
Write a recursive formula for each sequence.
7. 80, -40, 20, -10, …
8. 87, 52, 17, -18, …
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
a 1 = 80, a n = -0.5a n - 1, n ≥ 2
1 4 16 64
9. −
, −, −, −, …
3 15 75 375
a 1 = 87, a n = a n - 1 - 35, n ≥ 2
7
4 3
1
10. −
, −, - −
, -−
,…
5 10
1
4
a1 = −
, an = −
a
,n≥2
5 n-1
3
11. 2.6, 5.2, 7.8, 10.4, …
5
10
4
1
a1 = −
, an = an - 1 - −
,n≥2
5
2
12. 100, 120, 144, 172.8, …
a 1 = 2.6, a n = a n - 1 + 2.6, n ≥ 2
a 1 = 100, a n = 1.2a n - 1, n ≥ 2
13. PIZZA The total costs for ordering one to five cheese
pizzas from Luigi’s Pizza Palace are shown.
a. Write a recursive formula for the sequence.
a 1 = 7, a n = a n - 1 + 5.5, n ≥ 2
b. Write an explicit formula for the sequence.
Total Number of
Pizzas Ordered
Cost
1
2
3
4
5
$7.00
$12.50
$18.00
$23.50
$29.00
an = 5.5n + 1.5
Chapter 7
51
Glencoe Algebra 1
Lesson 7-8
1. a 1 = 25, a n = a n - 1 - 12, n ≥ 2