Proving a Limit Using the Definition of a Limit

In summary, the conversation is about using the definition of a limit to prove a given equation and the attempt at a solution provided by the person asking for feedback. The summary also states that the solution provided is correct.
  • #1
azatkgz
186
0
Please,check my solution.

Homework Statement


Use definition of a Limit to prove it.
[tex]\lim_{n\rightarrow\infty}\frac{2n^2-\sqrt{n}}{3n^2+5logn}=\frac{2}{3}[/tex]

The Attempt at a Solution



for [tex]\forall\epsilon>0[/tex] [tex]\exists N[/tex] such that [tex]\forall n>N[/tex]
we have
[tex]|\frac{2n^2-\sqrt{n}}{3n^2+5logn}-\frac{2}{3}|<\epsilon[/tex]

[tex]\frac{\sqrt{n}}{8n^2}<|\frac{-3\sqrt{n}-10logn}{3(3n^2+5n)}|<\epsilon[/tex]

We can choose [tex]N=\frac{1}{4\epsilon^{2/3}}[/tex]
 
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  • #2
Since, for n>N, we have \frac{\sqrt{n}}{8n^2}<\frac{1}{4\epsilon^{2/3}}<\epsilon Therefore, |\frac{2n^2-\sqrt{n}}{3n^2+5logn}-\frac{2}{3}|<\epsilonHence, \lim_{n\rightarrow\infty}\frac{2n^2-\sqrt{n}}{3n^2+5logn}=\frac{2}{3}Yes, your solution is correct.
 

1. What is the definition of a limit?

The definition of a limit is a mathematical concept that describes the behavior of a function as the input values approach a certain value. It is used to determine the value that a function approaches as its input approaches a specific value.

2. Why is the concept of a limit important?

The concept of a limit is important because it allows us to understand and analyze the behavior of functions, especially at points where the function may not be defined. It also helps us to make predictions and approximations in many real-world applications.

3. How is a limit written mathematically?

A limit is written mathematically as:
limx→a f(x) = L
This means that as the input value x approaches the value a, the output value of the function f(x) approaches the value L.

4. What are the two types of limits?

The two types of limits are:
1) One-sided limit: This is when the input values approach a specific value from either the left or the right side.
2) Two-sided limit: This is when the input values approach a specific value from both the left and the right side.

5. How is the limit of a function calculated?

The limit of a function can be calculated using algebraic manipulation, graphing, or using specific limit laws and theorems. Generally, we evaluate the function at values close to the desired input value and observe the behavior of the output values. If the output values approach a specific value, then that value is the limit of the function at that point.

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