Math Problem Statement

limx(xx2+12)\lim_{x\rarr\infty}\left(\frac{x}{\sqrt[2]{x^2+1}}\right)

Solution

Let's evaluate the following limit:

limx(xx2+1)\lim_{x \to \infty} \left(\frac{x}{\sqrt{x^2 + 1}}\right)

Step 1: Factor the denominator

Notice that the expression inside the square root in the denominator is x2+1x^2 + 1. To simplify the limit as xx \to \infty, let's factor x2x^2 from inside the square root:

x2+1=x2(1+1x2)=x1+1x2\sqrt{x^2 + 1} = \sqrt{x^2 \left( 1 + \frac{1}{x^2} \right)} = |x|\sqrt{1 + \frac{1}{x^2}}

For large xx, we know that x=x|x| = x (since xx is positive as xx \to \infty). Therefore, we can rewrite the expression as:

xx2+1=xx1+1x2=11+1x2\frac{x}{\sqrt{x^2 + 1}} = \frac{x}{x\sqrt{1 + \frac{1}{x^2}}} = \frac{1}{\sqrt{1 + \frac{1}{x^2}}}

Step 2: Take the limit

Now, as xx \to \infty, the term 1x2\frac{1}{x^2} becomes very small, and we have:

limx11+1x2=11+0=1\lim_{x \to \infty} \frac{1}{\sqrt{1 + \frac{1}{x^2}}} = \frac{1}{\sqrt{1 + 0}} = 1

Final Answer:

limx(xx2+1)=1\lim_{x \to \infty} \left(\frac{x}{\sqrt{x^2 + 1}}\right) = 1

Would you like more details on this process or have any questions? Here are some related questions to expand on this topic:

  1. What happens to the limit of xx2+c\frac{x}{\sqrt{x^2 + c}} for different constants cc?
  2. How do you evaluate limits that involve square roots in the denominator?
  3. What happens to the limit limx(1x2+1)\lim_{x \to \infty} \left( \frac{1}{\sqrt{x^2 + 1}} \right)?
  4. How can this type of limit be generalized for functions of the form p(x)q(x)\frac{p(x)}{q(x)} where both p(x)p(x) and q(x)q(x) are polynomials?
  5. What is the meaning of the square root approximation 1+ϵ1+ϵ2\sqrt{1 + \epsilon} \approx 1 + \frac{\epsilon}{2} for small ϵ\epsilon?

Tip: Whenever you have a square root involving a large variable, like xx, try factoring out the highest power of xx inside the square root. This often simplifies the expression, especially in limits as xx \to \infty.

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Math Problem Analysis

Mathematical Concepts

Limits
Square Roots
Asymptotic Behavior

Formulas

\lim_{x\to\infty} \frac{x}{\sqrt{x^2 + 1}}

Theorems

Limit of rational functions as x approaches infinity

Suitable Grade Level

Grades 10-12