Math Problem Statement

Find the limit of the function as x approaches negative infinity: lim(x → -∞) (√(2x² + 3) / (2x + 3)).

Solution

The problem is asking for the limit of the function as xx approaches negative infinity:

limx2x2+32x+3\lim_{x \to -\infty} \frac{\sqrt{2x^2 + 3}}{2x + 3}

Solution:

  1. Simplify the Expression:

    • First, notice that as xx becomes very large in magnitude (negatively), the term 2x22x^2 dominates over the constant terms 33 in both the numerator and the denominator.
    • We can factor x2x^2 out of the square root in the numerator.

    2x2+32x+3=x2(2+3x2)2x+3=x2+3x22x+3\frac{\sqrt{2x^2 + 3}}{2x + 3} = \frac{\sqrt{x^2(2 + \frac{3}{x^2})}}{2x + 3} = \frac{|x|\sqrt{2 + \frac{3}{x^2}}}{2x + 3}

  2. Consider the Sign of xx:

    • Since xx is approaching -\infty, x=x|x| = -x. So the expression becomes:

    x2+3x22x+3\frac{-x\sqrt{2 + \frac{3}{x^2}}}{2x + 3}

  3. Simplify Further:

    • Divide both the numerator and the denominator by xx:

    2+3x22+3x\frac{-\sqrt{2 + \frac{3}{x^2}}}{2 + \frac{3}{x}}

  4. Evaluate the Limit:

    • As xx \to -\infty, 3x2\frac{3}{x^2} and 3x\frac{3}{x} approach 0, simplifying the expression to:

    22\frac{-\sqrt{2}}{2}

    • Therefore, the limit is:

    limx2x2+32x+3=22\lim_{x \to -\infty} \frac{\sqrt{2x^2 + 3}}{2x + 3} = -\frac{\sqrt{2}}{2}

Would you like more details, or do you have any questions about this solution?

Related Questions:

  1. How does the behavior of the function change as xx approaches positive infinity instead of negative infinity?
  2. What is the importance of considering the sign of xx when dealing with absolute values in limits?
  3. Can you explain why we factor x2x^2 out of the square root in the numerator?
  4. How would the limit change if the constant in the numerator was a different value?
  5. What happens to the limit if the term 2x2+3\sqrt{2x^2 + 3} was replaced with x4+3\sqrt{x^4 + 3}?

Tip:

When dealing with limits involving infinity, simplifying the expression by factoring out the highest power of xx can often make the limit more straightforward to evaluate.

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Math Problem Analysis

Mathematical Concepts

Limits
Calculus
Algebraic Simplification

Formulas

Limit formula
Algebraic simplification

Theorems

Properties of Limits
Dominance of Leading Terms

Suitable Grade Level

Grades 11-12 or College Calculus