Math Problem Statement

solve

lim (x -> ∞) [(8x^2 - 3) / (7x^2 + x - 3)]

Solution

The given limit is:

limx8x237x2+x3\lim_{x \to \infty} \frac{8x^2 - 3}{7x^2 + x - 3}

Step-by-step solution:

  1. Factor the highest degree of xx from both the numerator and the denominator. The highest power of xx in this case is x2x^2.

    8x237x2+x3=x2(83x2)x2(7+1x3x2)\frac{8x^2 - 3}{7x^2 + x - 3} = \frac{x^2(8 - \frac{3}{x^2})}{x^2(7 + \frac{1}{x} - \frac{3}{x^2})}

  2. Simplify the expression by canceling out x2x^2 from both the numerator and denominator:

    =83x27+1x3x2= \frac{8 - \frac{3}{x^2}}{7 + \frac{1}{x} - \frac{3}{x^2}}

  3. Evaluate the limit as xx \to \infty. Notice that as xx becomes larger, terms like 1x\frac{1}{x} and 1x2\frac{1}{x^2} approach 0.

    • 3x20\frac{3}{x^2} \to 0
    • 1x0\frac{1}{x} \to 0

    Thus, the expression simplifies to:

    807+00=87\frac{8 - 0}{7 + 0 - 0} = \frac{8}{7}

Final Answer:

limx8x237x2+x3=87\lim_{x \to \infty} \frac{8x^2 - 3}{7x^2 + x - 3} = \frac{8}{7}

Would you like more details or have any questions? Here are some related questions to explore:

  1. What happens if the degree of the numerator is lower than the denominator when finding limits at infinity?
  2. How does dividing each term by the highest power of xx help in simplifying limits at infinity?
  3. What are the limits of functions as xx \to -\infty?
  4. Can we apply the same method for rational functions with higher degrees, like x3x^3?
  5. How would the limit change if we had a linear term in both the numerator and denominator?

Tip: When evaluating limits at infinity, always check the highest power of xx in both the numerator and the denominator—this helps to simplify the expression quickly!

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Math Problem Analysis

Mathematical Concepts

Calculus
Limits at Infinity
Rational Functions

Formulas

lim (x -> ∞) [f(x)/g(x)] = lim (x -> ∞) [f(x)/g(x)] after dividing by the highest power of x
When x -> ∞, terms with 1/x^n approach 0.

Theorems

Limits at Infinity Theorem
Simplifying Rational Functions at Infinity

Suitable Grade Level

Grades 11-12 (Calculus, Pre-Calculus)