Math Problem Statement

Find the limit of the function as x approaches infinity: lim (x → ∞) (x^2 + 3x - 18) / (x^2 + 6x).

Solution

The problem you uploaded asks to find the limit of the rational function as xx \to \infty:

limxx2+3x18x2+6x.\lim_{x \to \infty} \frac{x^2 + 3x - 18}{x^2 + 6x}.

Step-by-Step Solution:

  1. Identify the degrees of the polynomials:

    • The numerator is x2+3x18x^2 + 3x - 18, which is a quadratic function of degree 2.
    • The denominator is x2+6xx^2 + 6x, which is also a quadratic function of degree 2.
  2. Divide both the numerator and the denominator by the highest power of xx, which is x2x^2:

limxx2+3x18x2+6x=limxx2x2+3xx218x2x2x2+6xx2.\lim_{x \to \infty} \frac{x^2 + 3x - 18}{x^2 + 6x} = \lim_{x \to \infty} \frac{\frac{x^2}{x^2} + \frac{3x}{x^2} - \frac{18}{x^2}}{\frac{x^2}{x^2} + \frac{6x}{x^2}}.

  1. Simplify each term: =limx1+3x18x21+6x.= \lim_{x \to \infty} \frac{1 + \frac{3}{x} - \frac{18}{x^2}}{1 + \frac{6}{x}}.

  2. Evaluate the limit as xx \to \infty:

    • As xx \to \infty, terms with 1x\frac{1}{x} or higher powers of xx will approach 0. Therefore: =1+001+0=11.= \frac{1 + 0 - 0}{1 + 0} = \frac{1}{1}.
  3. Conclusion: limxx2+3x18x2+6x=1.\lim_{x \to \infty} \frac{x^2 + 3x - 18}{x^2 + 6x} = 1.

Would you like further clarification or a breakdown of any part of the process?

Related Questions:

  1. What happens if the degree of the numerator is greater than the degree of the denominator?
  2. How does the limit change if you evaluate the function as xx \to -\infty?
  3. What is the limit if a constant term is added to the denominator instead of a linear term?
  4. Can you apply L'Hopital's Rule to solve this limit, and how would it work?
  5. How do limits behave for rational functions where the degrees are not equal?

Tip: For rational functions, when the degree of the numerator and denominator are equal, the limit as xx \to \infty is determined by the ratio of the leading coefficients.

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Math Problem Analysis

Mathematical Concepts

Limits
Rational Functions
Algebra

Formulas

lim (x → ∞) f(x) = L if the degrees of numerator and denominator are equal

Theorems

Limit of rational functions as x approaches infinity

Suitable Grade Level

Grade 11-12 or Introductory College