Answer :
Answer: In Exercises 21 and 22, describe and correct the error in writing a rule for the nth term of the arithmetic sequence 22, 9, −4, −17, −30, . . ..
3. 1, −1, −3, −5, −7, . . . 4.
5. 5, 8, 13, 20, 29, . . . 6.
7. 36, 18, 9, —9, —9, . . . 8. 24
9. —1, —3, 1, —5, —3, . . . 10. 24 42
12, 6, 0, −6, −12, . . .
3, 5, 9, 15, 23, . . .
81, 27, 9, 3, 1, . . .
—1 , —1 , —5 , —7 , —3 , . . . 62662
21.
22. ✗
11. WRITING EQUATIONS Write a rule for the arithmetic sequence with the given description.
a. The first term is −3 and each term is 6 less than the previous term.
b. The first term is 7 and each term is 5 more than the previous term.
12. WRITING Compare the terms of an arithmetic sequence when d > 0 to when d < 0.
In Exercises 13–20, write a rule for the nth term of the sequence. Then find a20. (See Example 2.)
The first term is 22 and the common difference is −13.
an =−13+(n−1)(22) an =−35+22n
13. 12, 20, 28, 36, . . . 14. 15. 51, 48, 45, 42, . . . 16.
7, 12, 17, 22, . . .
27. a =−5,d=−—1
17 2 21 2
86, 79, 72, 65, . . . 11 511
29. USING EQUATIONS One term of an arithmetic sequence is a8 = −13. The common difference
is −8. What is a rule for the nth term of the sequence?
○A an = 51 + 8n ○B an = 35 + 8n ○C an=51−8n ○D an=35−8n
17. −1, −—3, —3, 1, . . . 18. 19. 2.3, 1.5, 0.7, −0.1, . . . 20.
−2, −—4, −—2, —4, . . . 11.7, 10.8, 9.9, 9, . . .
422 Chapter 8 Sequences and Series
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Use a1 = 22 and d = −13. a =a +nd
In Exercises 23–28, write a rule for the nth term of th
Step-by-step explanation: