Math Problem Statement

Выберите все верные варианты среди предложенных пределов.

Solution

The image shows a series of limit problems with instructions in Russian, asking to "Select all the correct options." I will evaluate each limit step by step:

  1. limnn2+n+2n3=1\lim_{n \to \infty} \frac{n^2 + n + 2}{n^3} = 1
    Solution:
    The dominant term in the numerator is n2n^2, and in the denominator, it is n3n^3.
    So, n2+n+2n3n2n3=1n0\frac{n^2 + n + 2}{n^3} \approx \frac{n^2}{n^3} = \frac{1}{n} \to 0.
    Therefore, this is false.

  2. limn(nn+1)=\lim_{n \to \infty} \left( \sqrt{n} - \sqrt{n+1} \right) = \infty
    Solution:
    We can simplify this by multiplying by the conjugate:
    nn+1=(nn+1)(n+n+1)n+n+1=1n+n+1\sqrt{n} - \sqrt{n+1} = \frac{(\sqrt{n} - \sqrt{n+1})(\sqrt{n} + \sqrt{n+1})}{\sqrt{n} + \sqrt{n+1}} = \frac{-1}{\sqrt{n} + \sqrt{n+1}} As nn \to \infty, this expression tends to 00.
    So, this is false.

  3. limn(1+1n3)n2=e\lim_{n \to \infty} \left( 1 + \frac{1}{n^3} \right)^{n^2} = e
    Solution:
    This is a standard form of a limit resembling the expression for ee. The expression approaches ee because for large nn, the term 1n3\frac{1}{n^3} tends to 0 slowly.
    Thus, this is true.

  4. limnn2+n+2n3=0\lim_{n \to \infty} \frac{n^2 + n + 2}{n^3} = 0
    Solution:
    As discussed in the first case, this limit is indeed 00, not 11.
    Therefore, this is true.

  5. limn(nn+1)=0\lim_{n \to \infty} \left( \sqrt{n} - \sqrt{n+1} \right) = 0
    Solution:
    From the second case, we determined that the expression tends to 0.
    So, this is true.

  6. limn(1+1n3)n2=1\lim_{n \to \infty} \left( 1 + \frac{1}{n^3} \right)^{n^2} = 1
    Solution:
    This does not approach 1, as the expression behaves similarly to the one for ee.
    Hence, this is false.

Correct answers:

  • limn(1+1n3)n2=e\lim_{n \to \infty} \left( 1 + \frac{1}{n^3} \right)^{n^2} = e (true)
  • limnn2+n+2n3=0\lim_{n \to \infty} \frac{n^2 + n + 2}{n^3} = 0 (true)
  • limn(nn+1)=0\lim_{n \to \infty} \left( \sqrt{n} - \sqrt{n+1} \right) = 0 (true)

Do you want more details or have any other questions?

Here are 5 related questions:

  1. How can limits help in evaluating indeterminate forms?
  2. What techniques can simplify limits involving square roots?
  3. How does L'Hopital's Rule work in solving limits?
  4. How is the concept of "dominant terms" useful in evaluating limits?
  5. How do limits behave for exponential forms like exe^x?

Tip: Always check for indeterminate forms like 00\frac{0}{0} or \infty - \infty when solving limits, as they often require special techniques like L'Hopital's Rule or simplification through algebraic manipulation.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Limits
Asymptotic Behavior
Square Roots
Exponential Growth

Formulas

lim_{n→∞} \frac{n^2 + n + 2}{n^3}
lim_{n→∞} (√n - √(n+1))
lim_{n→∞} \left(1 + \frac{1}{n^3}\right)^{n^2}

Theorems

Dominant Term Theorem
Limit of Exponential Expressions
Asymptotic Expansions

Suitable Grade Level

University-Level Calculus