Using a Theorem In Exercises 61-64, (a) use Theorem 9.5 a graphing utility to graph the first 10 terms of the to show that the sequence with the given nth term converges, Using and (b) use a 1 62. an %3D 61. a, = 7 + 2 = 5 - n

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to show that the sequence with the given nth term converges,
and (b) use a graphing utility to graph the first 10 terms of the
Using a Theorem In Exercises 61-64, (a) use Theorem 9.5
3)
55. a
58. а,
%3D
57. a, =
60. а, —
Cos n
59, a, = sin
In Exercises 61-64, (a) use Theorem 9.5
and (b) use a
and find its limit.
sequence
1
61. a, = 7 +-
2
62. a, = 5 -
n
1
63. an
1
3",
1
64. а, 3 2 +
%3D
5n
65. Increasing Sequence Let {a,} be an increasing
sequence such that 2 < a, < 4. Explain why {a,} has a limit.
What can you conclude about the limit?
66. Monotonic Sequence Let {a,} be a monotonic
sequence such that a, < 1. Discuss the convergence of {a,}.
When {a,} converges, what can you conclude about its limit?
67. Compound Interest • • • ..
Consider the sequence
{A,} whose nth term is
given by
HB 3446
82
L34348
L12
12
who
Transcribed Image Text:to show that the sequence with the given nth term converges, and (b) use a graphing utility to graph the first 10 terms of the Using a Theorem In Exercises 61-64, (a) use Theorem 9.5 3) 55. a 58. а, %3D 57. a, = 60. а, — Cos n 59, a, = sin In Exercises 61-64, (a) use Theorem 9.5 and (b) use a and find its limit. sequence 1 61. a, = 7 +- 2 62. a, = 5 - n 1 63. an 1 3", 1 64. а, 3 2 + %3D 5n 65. Increasing Sequence Let {a,} be an increasing sequence such that 2 < a, < 4. Explain why {a,} has a limit. What can you conclude about the limit? 66. Monotonic Sequence Let {a,} be a monotonic sequence such that a, < 1. Discuss the convergence of {a,}. When {a,} converges, what can you conclude about its limit? 67. Compound Interest • • • .. Consider the sequence {A,} whose nth term is given by HB 3446 82 L34348 L12 12 who
2. A sequence {a,} is bounded below when there is a real number N such that
Ns a, for all n. The number N is called a lower bound of the sequence.
3. A sequence (a,} is bounded when it is bounded above and bounded below.
Note that all three sequences in Example 3 (and shown in Figure 9.3) are bounde
o see this, note that
2 s a, s 4, Is b, s 2, and 0s c, s
3
One important property of the real numbers is that they are comp
nformally, this means that there are no holes or gaps on the real number line. (TH
of rational numbers does not have the completeness property.) The completeness E
or real numbers can be used to conclude that if a sequence has an upper bound
t must have a least upper bound (an upper bound that is less than all
apper bounds for the sequence). For example, the least upper bound of the se
a,} = {n/(n + 1)},
1 2 3 4
2 3 4' 5
n + 1'
is 1. The completeness axiom is used in the proof of Theorem 9.5.
THEOREM 9.5
Bounded Monotonic Sequences
If a sequence {a,} is bounded and monotonic, then it converges.
Proof Assume that the sequence is nondecreasing, as shown in Figure
sake of simplicity, also assume that each term in the sequence is positive
sequence is bounded, there must exist an upper bound M such that
aj s a, < az3 <.·< a,s...< M.
From the completeness axiom, it follows that there is a least upper bou
< a, s... < L.
a, s az s a3 s.
For e > 0, it follows thatL- E < L, and therefore L - e cannot be
for the sequence. Consequently, at least one term of {a,} is greater tha
L - ɛ < a, for some positive integer N. Because the terms of {a,} ar
it follows that ay s a, for n > N. You now know that L-
for every n > N. It follows that a, - L < e for n > N, which by det
{a,} converges to L. The proof for a nonincreasing sequence is similar
See LarsonCalculus.com for Bruce Edwards's video of this proof.
EくayS
Bounded and Monotonic Sequenc
EXAMPLE 9
{1/n} is both bounded and monotonic, an
Transcribed Image Text:2. A sequence {a,} is bounded below when there is a real number N such that Ns a, for all n. The number N is called a lower bound of the sequence. 3. A sequence (a,} is bounded when it is bounded above and bounded below. Note that all three sequences in Example 3 (and shown in Figure 9.3) are bounde o see this, note that 2 s a, s 4, Is b, s 2, and 0s c, s 3 One important property of the real numbers is that they are comp nformally, this means that there are no holes or gaps on the real number line. (TH of rational numbers does not have the completeness property.) The completeness E or real numbers can be used to conclude that if a sequence has an upper bound t must have a least upper bound (an upper bound that is less than all apper bounds for the sequence). For example, the least upper bound of the se a,} = {n/(n + 1)}, 1 2 3 4 2 3 4' 5 n + 1' is 1. The completeness axiom is used in the proof of Theorem 9.5. THEOREM 9.5 Bounded Monotonic Sequences If a sequence {a,} is bounded and monotonic, then it converges. Proof Assume that the sequence is nondecreasing, as shown in Figure sake of simplicity, also assume that each term in the sequence is positive sequence is bounded, there must exist an upper bound M such that aj s a, < az3 <.·< a,s...< M. From the completeness axiom, it follows that there is a least upper bou < a, s... < L. a, s az s a3 s. For e > 0, it follows thatL- E < L, and therefore L - e cannot be for the sequence. Consequently, at least one term of {a,} is greater tha L - ɛ < a, for some positive integer N. Because the terms of {a,} ar it follows that ay s a, for n > N. You now know that L- for every n > N. It follows that a, - L < e for n > N, which by det {a,} converges to L. The proof for a nonincreasing sequence is similar See LarsonCalculus.com for Bruce Edwards's video of this proof. EくayS Bounded and Monotonic Sequenc EXAMPLE 9 {1/n} is both bounded and monotonic, an
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