Limit of a Rational Function without L'Hospital's Rule

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In summary, when finding the limit of (e^xsin(x)-x-x^2)/(x^3 +xln(1-x)) as x approaches 0, the individual Mclaurin series for e^x and sinx were first substituted, followed by taking x^3 as a common factor and evaluating the limit. The resulting answer is 1/3, which was confirmed by another person. However, upon further discussion, it was noted that there is an x^2 term in the denominator that was not accounted for, resulting in a slightly incorrect answer. The correct answer is 0.
  • #1
jokerzz
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Lim x-> 0 (e^xsin(x)-x-x^2)/(x^3 +xln(1-x))


I first put the Mclaurin series of e^x and sinx and then took x^3 common and then put the limit. My answer comes out to be 1/3. Can anyone confirm whether I've done it right?
 
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  • #2
jokerzz said:
Lim x-> 0 (e^xsin(x)-x-x^2)/(x^3 +xln(1-x))


I first put the Mclaurin series of e^x and sinx and then took x^3 common and then put the limit. My answer comes out to be 1/3. Can anyone confirm whether I've done it right?

It would help if you showed a little more of the details, but there is an x^2 term in the denominator as well, isn't there? What did you do with that?
 
  • #3
I think your answer is a third too big.
 
  • #4
Dick said:
It would help if you showed a little more of the details, but there is an x^2 term in the denominator as well, isn't there? What did you do with that?

no there's no x^2. When you put x=0 at the end after substituting the mclaurin series of e^x and sinx, everything becomes 0, except -1/3! + 1/2 which is equal to 1/3
 
  • #5
Unit said:
I think your answer is a third too big.


the answer's 0?
 
  • #6
What do you get for the Mclaurin series for the denominator?
 
  • #7
jokerzz said:
no there's no x^2. When you put x=0 at the end after substituting the mclaurin series of e^x and sinx, everything becomes 0, except -1/3! + 1/2 which is equal to 1/3

There's an x^2 in the expansion of x*log(1-x).
 

1. What is the limit without using L'Hospital's rule?

The limit without using L'Hospital's rule is a method of finding the limit of a function at a certain point without using derivatives. It involves algebraic manipulation and simplification of the function to determine the limit.

2. When should I use the limit without L'Hospital's rule?

The limit without L'Hospital's rule should be used when the function is indeterminate at the given point, meaning that both the numerator and denominator approach zero or infinity.

3. How do I find the limit without using L'Hospital's rule?

To find the limit without using L'Hospital's rule, you will need to perform algebraic manipulations on the function to simplify it. This may involve factoring, cancelling out common terms, or using other algebraic techniques to rewrite the function in a simpler form.

4. What are the benefits of using the limit without L'Hospital's rule?

Using the limit without L'Hospital's rule can help deepen your understanding of limits and how they relate to derivatives. It also allows you to solve for limits at points where L'Hospital's rule cannot be used, such as when the function is not differentiable at the given point.

5. Are there any limitations to using the limit without L'Hospital's rule?

While the limit without L'Hospital's rule can be a useful tool, it may not always be the most efficient method for finding limits. In some cases, using L'Hospital's rule or other techniques may be quicker and easier. Additionally, this method may not work for all types of functions, so it is important to consider other approaches as well.

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