Math Problem Statement

What is the limit of (2 - 3x) / (1 - 5x) as x approaches infinity?

Solution

We are asked to find the limit:

limx23x15x\lim_{x \to \infty} \frac{2 - 3x}{1 - 5x}

Step 1: Identify Dominant Terms

As xx approaches infinity, the terms with the highest powers of xx in both the numerator and the denominator will dominate. The expression can be approximated by focusing on the dominant terms.

  • In the numerator, 3x-3x dominates over 22.
  • In the denominator, 5x-5x dominates over 11.

Step 2: Simplify the Expression

Now, simplify the expression by dividing both the numerator and the denominator by xx:

23x15x=2x31x5\frac{2 - 3x}{1 - 5x} = \frac{\frac{2}{x} - 3}{\frac{1}{x} - 5}

As xx \to \infty, both 2x\frac{2}{x} and 1x\frac{1}{x} approach zero. This simplifies the expression to:

0305=35=35\frac{0 - 3}{0 - 5} = \frac{-3}{-5} = \frac{3}{5}

Final Answer:

limx23x15x=35\lim_{x \to \infty} \frac{2 - 3x}{1 - 5x} = \frac{3}{5}

Let me know if you'd like any further clarification or details!


Here are 5 related questions for further exploration:

  1. What happens if we change the signs in the numerator or denominator?
  2. How does the limit behave if the powers of xx in the numerator and denominator are different?
  3. What is the limit of 2+3x1+5x\frac{2 + 3x}{1 + 5x} as xx \to \infty?
  4. Can you apply L'Hopital's Rule to find the limit instead of dividing by the highest power of xx?
  5. How would the limit change if we were considering xx \to -\infty?

Tip: When finding limits involving rational expressions at infinity, always focus on the highest degree terms in both the numerator and the denominator!

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Math Problem Analysis

Mathematical Concepts

Limits
Algebra
Rational Functions

Formulas

Limit as x approaches infinity of rational functions
Dominant term approximation

Theorems

Limits at infinity
Simplifying rational expressions

Suitable Grade Level

High School - Grades 10-12