Monotone conitnuous function - find limits

In summary, a monotone continuous function is a mathematical function that is both monotonic and continuous, meaning it has a consistent trend and no sudden jumps or gaps in its graph. The limits of a monotone continuous function can be determined by looking at its behavior as the input approaches a certain value. It can only have a single limit on either side of a specific point, but the limit may be undefined if the function has a vertical asymptote. To find the limits algebraically, you can use properties of limits and consider any vertical asymptotes or undefined points. Monotone continuous functions are important in mathematics because of their predictable and well-behaved graphs, real-world applications, and use in calculus.
  • #1
daniel_i_l
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Homework Statement


if f is monotonic and continues in R, and [tex]\int^{\infty}_{a} f(x)dx[/tex] converges then
[tex]lim_{x \rightarrow \infty} xf(x) = 0 [/tex]


Homework Equations





The Attempt at a Solution


I know that if xf(x) converges at all then it has to convergs to 0. But how do I know that it converges?
Thanks.
 
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  • #2
Can you show that for any positive value of k however small, that f(x)<k/x for all x>N for N sufficiently large? Hint: suppose it's not.
 
  • #3
Thanks.
 

1. What is a monotone continuous function?

A monotone continuous function is a type of mathematical function that is both monotonic (either strictly increasing or decreasing) and continuous. This means that the function has a consistent trend and there are no sudden jumps or gaps in its graph.

2. How do you determine the limits of a monotone continuous function?

The limits of a monotone continuous function can be determined by looking at the behavior of the function as the input approaches a certain value. For a strictly increasing function, the limit as x approaches infinity will be the maximum value of the function. Similarly, for a strictly decreasing function, the limit as x approaches negative infinity will be the minimum value of the function.

3. Can a monotone continuous function have multiple limits?

No, a monotone continuous function can only have a single limit on either side of a specific point. This is because the function has a consistent trend and does not have any sudden jumps or gaps in its graph. However, the limit as x approaches a specific point may be undefined if the function has a vertical asymptote at that point.

4. How do you find the limits of a monotone continuous function algebraically?

To find the limits of a monotone continuous function algebraically, you can use the properties of limits such as the sum, difference, product, and quotient rules. You can also use the squeeze theorem or L'Hopital's rule if necessary. It is important to also consider any vertical asymptotes or points where the function may be undefined.

5. Why are monotone continuous functions important in mathematics?

Monotone continuous functions are important in mathematics because they have predictable and well-behaved graphs, making them easy to analyze and understand. They also have many applications in real-world problems, such as in economics and physics. Additionally, monotone continuous functions are used in calculus to prove theorems and solve problems involving limits and derivatives.

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