Math Problem Statement

Evaluate the limit: lim (sqrt(n^5 + 3) - sqrt(n - 3)) / (sqrt[5]{n + 3} + sqrt(n + 3)) as n approaches infinity.

Solution

The limit problem in the image is as follows:

limn5+3n3n+35+n+3\lim \frac{\sqrt{n^5 + 3} - \sqrt{n - 3}}{\sqrt[5]{n + 3} + \sqrt{n + 3}}

Let's solve this limit as nn \to \infty.

Step 1: Analyze the numerator and denominator for large nn

  • For the numerator: n5+3n3\sqrt{n^5 + 3} - \sqrt{n - 3}

    • When nn is large, n5+3n^5 + 3 behaves like n5n^5, and n3n - 3 behaves like nn.
    • So, we approximate: n5+3n5=n5/2,n3n\sqrt{n^5 + 3} \approx \sqrt{n^5} = n^{5/2}, \quad \sqrt{n - 3} \approx \sqrt{n}

    The numerator approximately becomes: n5/2nn^{5/2} - \sqrt{n}

  • For the denominator: n+35+n+3\sqrt[5]{n + 3} + \sqrt{n + 3}

    • When nn is large, n+3n + 3 behaves like nn, so we approximate: n+35n1/5,n+3n\sqrt[5]{n + 3} \approx n^{1/5}, \quad \sqrt{n + 3} \approx \sqrt{n}

    The denominator approximately becomes: n1/5+nn^{1/5} + \sqrt{n}

Step 2: Simplify the limit expression

Now the expression looks like: limnn5/2nn1/5+n\lim_{n \to \infty} \frac{n^{5/2} - \sqrt{n}}{n^{1/5} + \sqrt{n}}

  • In the numerator, the term n5/2n^{5/2} dominates over n\sqrt{n} as nn \to \infty.
  • In the denominator, the term n\sqrt{n} dominates over n1/5n^{1/5}.

Thus, the limit becomes: limnn5/2n=limnn5/21/2=limnn2\lim_{n \to \infty} \frac{n^{5/2}}{\sqrt{n}} = \lim_{n \to \infty} n^{5/2 - 1/2} = \lim_{n \to \infty} n^2

As nn \to \infty, n2n^2 \to \infty, so the limit diverges to infinity.

Conclusion:

The limit does not converge to a finite value; instead, it goes to infinity.


Would you like more details, or have any questions about the steps?

Here are 5 related questions you could explore:

  1. How does the behavior of different power functions impact limits as nn \to \infty?
  2. Can L'Hopital's Rule be applied to limits of similar forms?
  3. What happens when the numerator and denominator grow at the same rate?
  4. How do we handle limits involving roots of polynomials with varying degrees?
  5. Can rationalization help simplify limits involving square roots?

Tip: When working with limits at infinity, always identify which terms dominate as nn grows large.

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Math Problem Analysis

Mathematical Concepts

Limits
Asymptotic Behavior
Simplification of Expressions

Formulas

Square root approximation
Dominant term analysis

Theorems

Limits at infinity

Suitable Grade Level

Grades 11-12