Limit at Infinity: Solve Without Squeeze Theorem

In summary, the conversation is about a limit equation \lim_{x \to \infty} \sqrt{x}\sin\frac{1}{x} and the use of the squeeze theorem. The person is studying for an exam and is questioning if the expansion of sinx is necessary for solving the equation. They also mention using substitution in similar problems. The response suggests using substitution by letting t = \frac{1}{x} to evaluate the limit as \mathop {\lim }\limits_{t \to 0} \frac{{\sin t}}{{\sqrt t }}. The person thanks for the help.
  • #1
mateomy
307
0

Homework Statement



[tex]
\lim_{x \to \infty} \sqrt{x}\sin\frac{1}{x}
[/tex]

Homework Equations


I don't think you can use the squeeze theorem here...

The Attempt at a Solution



So I am just studying for an exam that I have tomorrow and I am going through problems that weren't assigned on our homework set, (just in case he wants to slip something in there).

I was looking at the solution to the fore-mentioned limit equation and it references the expansion of sinx. Is this necessary? I've used substitution before in problems like lim as x approaches infinity of xsin(1\x) setting 1\x as y while t approaches zero. Can that sort of thing be done here?THANKS FOR ANY HELP!
 
Last edited:
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  • #2
To make things clearer:
let [tex]t = \frac{1}{x}[/tex]
an now the limit is
[tex]\mathop {\lim }\limits_{t \to 0} \frac{{\sin t}}{{\sqrt t }} = \mathop {\lim (}\limits_{t \to 0} \frac{{\sin t}}{t} \times \sqrt t )[/tex].
Now you shall see how to do it.
 
  • #3
Thank you!
 

Related to Limit at Infinity: Solve Without Squeeze Theorem

1. What is the concept of a limit at infinity?

The limit at infinity is a mathematical concept that describes the behavior of a function as the input variable approaches infinity. It is used to determine the value that a function approaches as its input grows without bound.

2. How is a limit at infinity solved without using the squeeze theorem?

A limit at infinity can be solved without using the squeeze theorem by using algebraic manipulation and the properties of limits. This involves simplifying the expression and evaluating the limit as the input variable approaches infinity.

3. What are the key steps for solving a limit at infinity?

The key steps for solving a limit at infinity include simplifying the expression, identifying any indeterminate forms (such as ∞/∞ or 0/0), applying limit laws and properties, and evaluating the limit as the input variable approaches infinity.

4. Can a limit at infinity have multiple solutions?

No, a limit at infinity can only have one solution. This is because the value that a function approaches as the input variable approaches infinity is a unique value, not multiple values.

5. What are some real-life applications of limits at infinity?

Limits at infinity are used in various fields such as physics, engineering, economics, and biology. They can be used to model the growth of populations, the trajectory of objects in motion, and the behavior of complex systems. They are also used in the study of rates of change and optimization problems.

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