Prove that all convergent sequences are bounded

In summary, the maximum of all the terms in the sequence plus the 1 + |A| term is used for the bound in order to account for cases where the first N terms are larger than the rest, and the absolute value is necessary to ensure that the bound applies to all terms.
  • #1
converting1
65
0
was looking at a proof of this here: http://gyazo.com/8e35dc1a651cec5948db1ab14df491f8

I have two questions,

why do you set K = max of all the terms of the sequence plus the 1 + |A| term? Why do you need the absolute value of all the terms? i.e. why |a_1| instead of |a_1|?
 
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  • #2
converting1 said:
was looking at a proof of this here: http://gyazo.com/8e35dc1a651cec5948db1ab14df491f8

I have two questions,

why do you set K = max of all the terms of the sequence plus the 1 + |A| term? Why do you need the absolute value of all the terms? i.e. why |a_1| instead of |a_1|?

Because ##|x_n|< L+1## only holds for ##n > N##. If some of the first ##N## terms are larger than all the rest, use the biggest one of them for the bound.
 

What does it mean for a sequence to be convergent?

When a sequence of numbers approaches a specific value as the number of terms increases, it is said to be convergent. This specific value is called the limit of the sequence.

What does it mean for a sequence to be bounded?

A bounded sequence is one in which all the terms fall within a specific range or are limited in their values. This means that the terms of the sequence do not increase or decrease indefinitely.

Why is it important to prove that all convergent sequences are bounded?

Proving that all convergent sequences are bounded is important because it helps us understand the behavior of sequences and their limits. It also allows us to make predictions about the terms of a sequence based on its limit.

How can we prove that all convergent sequences are bounded?

To prove that all convergent sequences are bounded, we can use the definition of convergence, which states that for a sequence to be convergent, it must approach a specific value (limit) as the number of terms increases. Using this definition, we can show that the terms of the sequence are limited to a specific range.

Can a sequence be convergent without being bounded?

No, a sequence cannot be convergent without being bounded. If a sequence is not bounded, it means that its terms are increasing or decreasing indefinitely, which goes against the definition of convergence. A sequence must have a limit (a specific value) for it to be convergent, and this limit is only possible if the terms are bounded.

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