Expanding Cube Roots: Solving Limits with Maclaurin Series

  • Context: Graduate 
  • Thread starter Thread starter snoopies622
  • Start date Start date
  • Tags Tags
    Cube Expanding Root
Click For Summary
SUMMARY

The forum discussion focuses on solving the limit problem using the Maclaurin series for the expression \(\lim_{x \to \infty} [ \sqrt[3]{x+1} - \sqrt[3]{x} ]\). The user successfully expands \(\sqrt[3]{x+1}\) using the Maclaurin series, resulting in the series \(1 + \frac{x}{3} - \frac{x^2}{9} + \frac{5x^3}{81} + \ldots\). The discussion highlights the realization that substituting \(y = x + 1\) simplifies the problem, allowing for a straightforward solution. The exchange emphasizes the importance of recognizing algebraic simplifications alongside series expansions.

PREREQUISITES
  • Understanding of limits in calculus
  • Familiarity with Maclaurin series expansions
  • Knowledge of cube roots and their properties
  • Basic algebraic manipulation techniques
NEXT STEPS
  • Study the derivation and applications of Maclaurin series in calculus
  • Explore advanced limit techniques, particularly for indeterminate forms
  • Learn about Taylor series and their convergence properties
  • Investigate algebraic methods for simplifying expressions involving roots
USEFUL FOR

Students of calculus, mathematics educators, and anyone interested in advanced limit-solving techniques using series expansions.

snoopies622
Messages
852
Reaction score
29
A quiz at the end of Steven Krantz's Calculus Demystified includes the following problem:
Find
<br /> \lim_{x \to \infty} [ \sqrt[3]{x+1}<br /> -<br /> \sqrt[3]{x} ]<br />
I see how one can use the Maclaurin series to get
<br /> \sqrt[3]{x+1} = 1 + \frac {x}{3} - \frac {x^2}{9} + \frac {5 x^3}{81} + . . .<br />
but trying it with the cube root of x gives me zero plus an endless series of undefined terms.
Is there a way to expand \sqrt[3]{x} and solve this problem?
 
Physics news on Phys.org
But why do you want expand that in series?
Isn't it by simple high school algebra :
ac{2}{3}&plus;%20%28x&plus;1%29^\frac{2}{3}&plus;x^{\frac{1}{3}}%28x&plus;1%29^{\frac{1}{3}}%20}.gif

for x>0?
 
Oh yeah, you're right zoki85 - thanks!

I also just realized that I could simply define y = x + 1, plug in y-1 for all the x's in the series above and there's the answer to my other question. :)
 

Similar threads

  • · Replies 3 ·
Replies
3
Views
4K
  • · Replies 6 ·
Replies
6
Views
4K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 1 ·
Replies
1
Views
3K
Replies
2
Views
2K
  • · Replies 17 ·
Replies
17
Views
5K
Replies
8
Views
2K