Math Problem Statement

Find the limit, if it exists: lim (x -> ∞) (5x - 3) / (2x + 9).

Solution

To solve the limit problem presented in the image, we need to evaluate the following limit:

limx5x32x+9\lim_{x \to \infty} \frac{5x - 3}{2x + 9}

Step-by-Step Solution:

  1. Analyze the degrees of the numerator and denominator:

    • The numerator is 5x35x - 3, and the highest degree term is 5x5x.
    • The denominator is 2x+92x + 9, and the highest degree term is 2x2x.

    Since both the numerator and denominator are of degree 1 (highest degree of xx is 1 in both cases), we can proceed by dividing both the numerator and denominator by xx, the highest power of xx in the expression.

  2. Rewrite the expression: limx5x32x+9=limx5xx3x2xx+9x\lim_{x \to \infty} \frac{5x - 3}{2x + 9} = \lim_{x \to \infty} \frac{\frac{5x}{x} - \frac{3}{x}}{\frac{2x}{x} + \frac{9}{x}} Simplifying this gives: limx53x2+9x\lim_{x \to \infty} \frac{5 - \frac{3}{x}}{2 + \frac{9}{x}}

  3. Take the limit as xx \to \infty:

    • As xx \to \infty, 3x0\frac{3}{x} \to 0 and 9x0\frac{9}{x} \to 0.
    • Thus, the expression becomes: 502+0=52\frac{5 - 0}{2 + 0} = \frac{5}{2}

Final Answer:

limx5x32x+9=52\lim_{x \to \infty} \frac{5x - 3}{2x + 9} = \frac{5}{2}

Let me know if you would like further clarification!


Here are 5 related questions for further exploration:

  1. How do you handle limits where the degree of the numerator is higher than the degree of the denominator?
  2. What is the result of a limit when the degrees of the numerator and denominator are different?
  3. How would the result change if there were higher powers of xx in the numerator and denominator?
  4. How can you find horizontal asymptotes using limits as xx \to \infty?
  5. What does it mean if the limit approaches infinity instead of a finite number?

Tip: Always compare the degrees of the numerator and denominator when evaluating limits of rational functions at infinity!

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Math Problem Analysis

Mathematical Concepts

Limits
Rational Functions
Calculus

Formulas

Limit of a rational function as x approaches infinity

Theorems

Properties of limits at infinity

Suitable Grade Level

Grades 11-12, College Calculus