Proving Convergence of Xn: Triangle Inequality & Examples

Thread starter alice 9
Start date Oct 6, 2010
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Convergence Inequality Triangle Triangle inequality

In summary, convergence in mathematics refers to the idea of a sequence approaching a specific value or limit as the number of terms or inputs increases. The triangle inequality helps in proving convergence by establishing an upper bound for the difference between consecutive terms in a sequence. An example of using the triangle inequality to prove convergence is the sequence xn = 1/n. Other common techniques used to prove convergence include the comparison test, ratio test, and root test. While a sequence may satisfy the triangle inequality, it may not necessarily converge as it must also meet other conditions.

Oct 6, 2010

alice 9

hi every body
show if Xn→x then lXnl→lxl hint use trangle inequality
2/ show
if lXnl→0 then Xn →0

show by example that lXnl fore all n in N MAY CONVERGE and Xn may not converge

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Oct 6, 2010

╔(σ_σ)╝

Use the triangle inequality.
||a|-|b||< |a-b|

These questions are extremely trivial.

Please show your work. We do not do your homework for you.

FAQ: Proving Convergence of Xn: Triangle Inequality & Examples

1. What is the definition of convergence in mathematics?

In mathematics, convergence refers to the idea that a sequence of values or functions approaches a specific value or limit as the number of terms or inputs increases.

2. How does the triangle inequality help in proving convergence of a sequence?

The triangle inequality states that the sum of the lengths of any two sides of a triangle is always greater than the length of the third side. This property is useful in proving convergence of a sequence because it helps to establish an upper bound for the difference between consecutive terms in the sequence.

3. Can you provide an example of using the triangle inequality to prove convergence?

One example of using the triangle inequality to prove convergence is the proof of the convergence of the sequence xn = 1/n. By applying the triangle inequality, we can show that the absolute value of the difference between consecutive terms in the sequence is always less than or equal to 1/n, which approaches 0 as n approaches infinity. Therefore, the sequence converges to 0.

4. What are some other common techniques used to prove convergence of a sequence?

Aside from using the triangle inequality, other common techniques used to prove convergence of a sequence include the comparison test, the ratio test, and the root test. These tests involve comparing the given sequence to a known convergent or divergent sequence, and using algebraic or limit calculations to determine the convergence of the original sequence.

5. Is it possible for a sequence to satisfy the triangle inequality but not converge?

Yes, it is possible for a sequence to satisfy the triangle inequality but not converge. The triangle inequality only provides an upper bound for the difference between consecutive terms in a sequence, but it does not guarantee the existence of a limit. In order for a sequence to converge, it must also satisfy other conditions, such as being bounded and monotonic.