Find the limit in question 7e and 7g?

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In summary, the conversation discusses finding limits in question 7e and 7g using real calculus. It is argued that the limit in question 7e must be zero due to the boundedness of the sine function, while the limit in question 7g can be derived by expanding the sine function around x approaching infinity. The conversation ends with a request for further explanation.
  • #1
haha1234
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How can I find the limit in question 7e and 7g?
Finding limits is difficult!:cry:
 

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  • #2
7e: I guess everything is within real calculus. Then you can argue that the sine is bound and thus the limit must be zero:
[tex]0 \leq |x \sin(1/x)| \leq |x| \rightarrow 0.[/tex]

7g: Expanding [itex]\sin(1/x)[/itex] around [itex]x \rightarrow \infty[/itex] gives
[tex]x \sin(1/x)=x [1/x+\mathcal{O}(1/x^3)] \rightarrow 1.[/tex]
 
  • #3
vanhees71 said:
7e: I guess everything is within real calculus. Then you can argue that the sine is bound and thus the limit must be zero:
[tex]0 \leq |x \sin(1/x)| \leq |x| \rightarrow 0.[/tex]

7g: Expanding [itex]\sin(1/x)[/itex] around [itex]x \rightarrow \infty[/itex] gives
[tex]x \sin(1/x)=x [1/x+\mathcal{O}(1/x^3)] \rightarrow 1.[/tex]

How to derive this?
Could you explain more,please?
 

Related to Find the limit in question 7e and 7g?

1. What is the purpose of finding the limit in question 7e and 7g?

The purpose of finding the limit in question 7e and 7g is to determine the value that a function approaches as the input approaches a certain value. This can help us understand the behavior of the function and make predictions about its values.

2. How do you find the limit in question 7e and 7g?

The limit can be found by substituting the given value into the function and simplifying the expression. If the resulting expression is undefined, we can use algebraic techniques such as factoring or rationalizing the denominator to determine the limit.

3. What do the numbers in the brackets or parentheses represent in question 7e and 7g?

The numbers in the brackets or parentheses represent the input values, or the values that are approaching the limit. For example, in question 7e, (x+2) represents the input values that are approaching the limit of x= -2.

4. Can the limit in question 7e and 7g be found algebraically or graphically?

Yes, the limit can be found both algebraically and graphically. Algebraic methods involve simplifying the expression and evaluating it at the given input value. Graphical methods involve plotting the function and observing the behavior near the input value to determine the limit.

5. How is finding the limit in question 7e and 7g useful in real-life applications?

Finding the limit can help us make predictions about the behavior of a system or process. For example, in physics, the limit of a function can represent the maximum or minimum value that a variable can reach, which can be useful in designing experiments or predicting outcomes. In economics, the limit can represent the maximum profit or minimum cost that a business can achieve, which can aid in decision making.

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