12.1 Infinite Sets The following theorem follows directly from our previous work with the NIP and will be very handy later. It basically says that a sequence of nested closed intervals will still have a non-empty intersection even if their lengths do not converge to zero as in the NIP. Theorem 12.1.1. Let ([an,bn]), be a sequence of nested intervals such that lim bn – an> 0. Then there is at least onec E R such that c E [an, bn] for all z=1 n E N. Proof. By Corollary 10.4.5 of Chapter 10, we know that a bounded increasing sequence such as (an) converges, say to c. Since an < am < b, for m > n and lim am = c, then for any fixed n, a, 0. Show that there are at least two points, c and d, such that c E [an, bn] and d E [an, bn] for all n E N.

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Real math analysis, Please help me solve problem 12.1.2

12.1 Infinite Sets
The following theorem follows directly from our previous work with the NIP and
will be very handy later. It basically says that a sequence of nested closed
intervals will still have a non-empty intersection even if their lengths do not
converge to zero as in the NIP.
Theorem 12.1.1. Let ([an, bn]), be a sequence of nested intervals such that
lim |bn
n=1
an > 0. Then there is at least one c E R such that c E [an, bn] for all
пEN.
Proof. By Corollary 10.4.5 of Chapter 10, we know that a bounded increasing
sequence such as (an) converges, say to c. Since an < am < bn for m > n and
= c, then for any fixed n, an <c< bn. This says c e [an, bn] for all n E N.
lim am
m→∞
Corollary 10.4.5. Let (xn) be a bounded, increasing sequence of real
numbers. That is, x1 < x2 < x3 <.…. Then (xn) converges to some real
number c.
in-context
Problem 12.1.2. Suppose lim |b,
0. Show that there are at least two
An
points, c and d, such that c E [an, bn] and d E [an, bn] for all n E N.
Transcribed Image Text:12.1 Infinite Sets The following theorem follows directly from our previous work with the NIP and will be very handy later. It basically says that a sequence of nested closed intervals will still have a non-empty intersection even if their lengths do not converge to zero as in the NIP. Theorem 12.1.1. Let ([an, bn]), be a sequence of nested intervals such that lim |bn n=1 an > 0. Then there is at least one c E R such that c E [an, bn] for all пEN. Proof. By Corollary 10.4.5 of Chapter 10, we know that a bounded increasing sequence such as (an) converges, say to c. Since an < am < bn for m > n and = c, then for any fixed n, an <c< bn. This says c e [an, bn] for all n E N. lim am m→∞ Corollary 10.4.5. Let (xn) be a bounded, increasing sequence of real numbers. That is, x1 < x2 < x3 <.…. Then (xn) converges to some real number c. in-context Problem 12.1.2. Suppose lim |b, 0. Show that there are at least two An points, c and d, such that c E [an, bn] and d E [an, bn] for all n E N.
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