Math Problem Statement

limite de cette suite

Solution

The sequence unu_n given in the image is defined by:

un=32n+17u_n = \frac{3}{2\sqrt{n} + 17}

To find the limit of this sequence as nn \to \infty, let's analyze the expression:

un=32n+17u_n = \frac{3}{2\sqrt{n} + 17}

As nn \to \infty, the term 2n2\sqrt{n} grows much faster than the constant 17. Therefore, the expression 2n+172\sqrt{n} + 17 is dominated by 2n2\sqrt{n} for large values of nn.

To find the limit, consider the asymptotic behavior:

limnun=limn32n+17\lim_{n \to \infty} u_n = \lim_{n \to \infty} \frac{3}{2\sqrt{n} + 17}

Since 2n2\sqrt{n} becomes very large as nn increases, the fraction approaches zero. Hence,

limnun=0\lim_{n \to \infty} u_n = 0

Thus, the limit of the sequence unu_n as nn \to \infty is 0.

Would you like more details on the steps taken, or do you have any specific questions?

Related Questions:

  1. How would the limit change if the sequence were un=32n17u_n = \frac{3}{2\sqrt{n} - 17}?
  2. What is the rate of convergence of the sequence un=32n+17u_n = \frac{3}{2\sqrt{n} + 17} to its limit?
  3. How do we compute the limit of a sequence where the term in the denominator grows exponentially, such as un=32n+17u_n = \frac{3}{2^n + 17}?
  4. How does the presence of a square root affect the convergence of a sequence?
  5. Can you find an nn after which unu_n becomes less than a given small positive number, say 0.010.01?

Tip:

When finding limits of sequences, it's often useful to compare terms in the denominator to determine which dominates as nn approaches infinity.

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Math Problem Analysis

Mathematical Concepts

Sequences
Limits
Asymptotic Analysis

Formulas

Limit of a sequence

Theorems

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Suitable Grade Level

Advanced High School