What Happens to the Limit of ln(x) + 1/x as x Approaches Zero from the Right?

In summary, the limit of ln x + 1/x as x approaches 0+ is -∞. However, the limit of xe^(1/x) does not exist as x approaches 0+.
  • #1
oswald88
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Homework Statement



Find limit lim x->0+ of lnx+1/x

Homework Equations



1/x = ln e^1/x

The Attempt at a Solution



ln x + ln e^1/x = ln x*e^(1/x)
lim x-> 0+

ln x + ln e^1/x = ln 0*inf = ln 0 = - inf
lim x-> 0+

Source: my self vs http://www.numberempire.com/limitcalculator.php
 

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  • #2


above, pitcure of mathematica solution..
 

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  • #3
oswald88 said:
ln x + ln e^1/x = ln x*e^(1/x)
lim x-> 0+

ln x + ln e^1/x = ln 0*inf = ln 0 = - inf
lim x-> 0+

[tex]\lim_{x\to x_0} f(x)g(x)=\left(\lim_{x\to x_0} f(x)\right)\left(\lim_{x\to x_0}g(x)\right)[/tex]

The above property is only true if both the individual limits exist (are finite). But, [tex]\lim_{x\to 0^+}e^{1/x}=\infty[/itex] which isn't finite, and so you can't claim that

[tex]\lim_{x\to 0^+}xe^{1/x}=\left(\lim_{x\to 0^+}x\right)\left(\lim_{x\to 0^+}e^{1/x}\right)=(0)(\infty)=0[/tex]
 

Related to What Happens to the Limit of ln(x) + 1/x as x Approaches Zero from the Right?

1. What is a limit ln function?

A limit ln function is a mathematical concept used to describe the behavior of a logarithmic function as the input approaches a certain value. It represents the maximum or minimum value that a logarithmic function can reach.

2. How do you find the limit of a ln function?

To find the limit of a ln function, you can use the properties of logarithms and the rules of limits. First, simplify the expression using logarithmic properties. Then, evaluate the limit using the rules of limits, such as the sum, difference, and product rules.

3. What are the rules for evaluating limits of ln functions?

The rules for evaluating limits of ln functions include the sum, difference, product, and quotient rules. These rules allow you to simplify the expression and evaluate the limit without directly substituting the value into the function.

4. Can the limit of a ln function be undefined?

Yes, the limit of a ln function can be undefined. This usually happens when the input approaches a value that results in taking the logarithm of a negative or zero number, which is undefined in mathematics.

5. How is the limit of a ln function used in real life?

The limit of a ln function is used in real life in various fields such as economics, physics, and engineering. For example, it is used to model the growth of populations, the decay of radioactive materials, and the spread of diseases. It is also used in financial applications, such as compound interest and investment growth.

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