Math Problem Statement

What is the limit of (2x√x - x + 3) / (3/x^2) as x approaches infinity?

Solution

We are given the limit:

limx2xxx+33x2\lim_{{x \to \infty}} \frac{2x \sqrt{x} - x + 3}{\frac{3}{x^{2}}}

Step 1: Simplify the denominator

First, notice that the denominator can be rewritten as:

3x2=3x2\frac{3}{x^2} = 3x^{-2}

So the expression becomes:

limx2xxx+33x2\lim_{{x \to \infty}} \frac{2x \sqrt{x} - x + 3}{3x^{-2}}

Step 2: Multiply numerator and denominator by x2x^2

To simplify further, we multiply both the numerator and the denominator by x2x^2, which eliminates the negative exponent in the denominator:

=limxx2(2xxx+3)3= \lim_{{x \to \infty}} \frac{x^2 (2x \sqrt{x} - x + 3)}{3}

Now, distribute x2x^2 in the numerator:

=limx2x3xx3+3x23= \lim_{{x \to \infty}} \frac{2x^3 \sqrt{x} - x^3 + 3x^2}{3}

Step 3: Focus on the highest powers of xx

Since we are taking the limit as xx approaches infinity, the terms with the highest powers of xx dominate the behavior of the expression. The term 2x3x2x^3 \sqrt{x} (which is actually 2x7/22x^{7/2}) will grow faster than the other terms as xx goes to infinity. Therefore, we focus on that leading term.

Step 4: Approximate the limit

The dominant term in the numerator is 2x7/22x^{7/2}. So, we approximate the limit as:

limx2x7/23=\lim_{{x \to \infty}} \frac{2x^{7/2}}{3} = \infty

Conclusion

The limit diverges to infinity:

\boxed{\infty}


Would you like further details on any of the steps or concepts involved? Here are some related questions for practice:

  1. What is the behavior of the function xxx \sqrt{x} as xx approaches infinity?
  2. How do you determine the dominant term when simplifying limits at infinity?
  3. How does multiplying by powers of xx affect the limit of a rational function?
  4. Can you explain why lower-order terms can be ignored when finding limits at infinity?
  5. How would you approach a limit problem where both numerator and denominator grow without bound?

Tip: When dealing with limits approaching infinity, focus on the highest-order term to determine the function's growth.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Limits at infinity
Asymptotic behavior
Simplification of rational expressions

Formulas

lim (x → ∞) f(x) / g(x)
Behavior of polynomial and root functions at infinity

Theorems

Dominance of higher powers in limits
Rules of limits at infinity

Suitable Grade Level

University level