Math Problem Statement

Find the limit of the sequence a_n = (9n^2 + 6n + 7) / (8n^2 + 4n + 2) as n approaches infinity.

Solution

To find the limit of the sequence

an=9n2+6n+78n2+4n+2a_n = \frac{9n^2 + 6n + 7}{8n^2 + 4n + 2}

as nn \to \infty, we analyze the terms by dividing both the numerator and denominator by n2n^2, the highest power of nn in the denominator:

limn9n2+6n+78n2+4n+2=limn9n2n2+6nn2+7n28n2n2+4nn2+2n2.\lim_{n \to \infty} \frac{9n^2 + 6n + 7}{8n^2 + 4n + 2} = \lim_{n \to \infty} \frac{\frac{9n^2}{n^2} + \frac{6n}{n^2} + \frac{7}{n^2}}{\frac{8n^2}{n^2} + \frac{4n}{n^2} + \frac{2}{n^2}}.

Simplify each term:

limn9+6n+7n28+4n+2n2.\lim_{n \to \infty} \frac{9 + \frac{6}{n} + \frac{7}{n^2}}{8 + \frac{4}{n} + \frac{2}{n^2}}.

As nn \to \infty, the terms 6n,7n2,4n,\frac{6}{n}, \frac{7}{n^2}, \frac{4}{n}, and 2n2\frac{2}{n^2} approach 0. This simplifies the expression to:

98.\frac{9}{8}.

Thus, the limit is:

98.\boxed{\frac{9}{8}}.


Would you like a more detailed step-by-step breakdown or further clarification?

Related Questions:

  1. How do you determine which term dominates as nn \to \infty?
  2. Why do we divide by the highest power of nn in the denominator?
  3. What happens if the highest powers in the numerator and denominator are not equal?
  4. How do limits behave when terms include logarithms or exponential growth?
  5. How can this method be applied to similar rational functions?

Tip:

Always check for the highest degree term in both numerator and denominator when evaluating limits of rational functions.

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Math Problem Analysis

Mathematical Concepts

Limits of sequences
Asymptotic behavior of rational functions

Formulas

lim_{n→∞} (P(n)/Q(n)) = leading coefficient of P(n) / leading coefficient of Q(n) for polynomials P(n) and Q(n)

Theorems

Polynomial degree dominance in limits

Suitable Grade Level

Grades 11-12