Math Problem Statement

Evaluate the limit: \( \lim_{{x \to 9}} \frac{x^2 + 6x - 27}{x + 9} \)

Solution

The problem involves finding the limit:

limx9x2+6x27x+9\lim_{{x \to 9}} \frac{x^2 + 6x - 27}{x + 9}

Step 1: Substitute x=9x = 9 directly

To see if direct substitution works, we plug x=9x = 9 into the expression:

92+69279+9=81+542718=10818=6\frac{9^2 + 6 \cdot 9 - 27}{9 + 9} = \frac{81 + 54 - 27}{18} = \frac{108}{18} = 6

Final Answer:

limx9x2+6x27x+9=6\lim_{{x \to 9}} \frac{x^2 + 6x - 27}{x + 9} = 6

Let me know if you have any questions, need further clarification, or want a deeper explanation of this problem.

Related Questions

  1. How would you solve the limit if direct substitution led to an indeterminate form?
  2. Can this limit be solved by factoring? Why or why not?
  3. What if the limit was x9x \to -9 instead?
  4. How do you find the limit of a rational function with a factorable numerator?
  5. What is the significance of limits in calculus?

Tip

Always check for direct substitution first in limit problems—it's the quickest method if it works!

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Math Problem Analysis

Mathematical Concepts

Limits
Direct Substitution
Rational Functions

Formulas

Limit definition: \( \lim_{{x \to a}} f(x) = L \) if direct substitution results in a defined value

Theorems

Limit evaluation using direct substitution

Suitable Grade Level

Grades 11-12