Math Problem Statement

Evaluate the limit as x approaches 3 of (1/(x-3) - 6/(x^2 - 3^2)).

Solution

The given limit expression is:

limx3(1x36x232)\lim_{x \to 3} \left( \frac{1}{x-3} - \frac{6}{x^2 - 3^2} \right)

Let's solve it step by step.

Step 1: Simplify the second fraction.

The denominator x232x^2 - 3^2 can be factored as a difference of squares: x232=(x3)(x+3)x^2 - 3^2 = (x - 3)(x + 3) Thus, the second term becomes: 6x232=6(x3)(x+3)\frac{6}{x^2 - 3^2} = \frac{6}{(x - 3)(x + 3)}

Step 2: Combine the two fractions.

The expression becomes: limx3(1x36(x3)(x+3))\lim_{x \to 3} \left( \frac{1}{x - 3} - \frac{6}{(x - 3)(x + 3)} \right) To combine these, we need a common denominator. The common denominator will be (x3)(x+3)(x - 3)(x + 3). Rewriting both fractions: 1x3=x+3(x3)(x+3)\frac{1}{x - 3} = \frac{x + 3}{(x - 3)(x + 3)} Thus, the expression becomes: limx3(x+3(x3)(x+3)6(x3)(x+3))\lim_{x \to 3} \left( \frac{x + 3}{(x - 3)(x + 3)} - \frac{6}{(x - 3)(x + 3)} \right) Now combine the numerators: (x+3)6(x3)(x+3)=x3(x3)(x+3)\frac{(x + 3) - 6}{(x - 3)(x + 3)} = \frac{x - 3}{(x - 3)(x + 3)}

Step 3: Simplify.

Cancel out the (x3)(x - 3) terms in the numerator and denominator: x3(x3)(x+3)=1x+3\frac{x - 3}{(x - 3)(x + 3)} = \frac{1}{x + 3}

Step 4: Evaluate the limit.

Now, evaluate the limit as x3x \to 3: limx31x+3=13+3=16\lim_{x \to 3} \frac{1}{x + 3} = \frac{1}{3 + 3} = \frac{1}{6}

Final Answer:

The value of the limit is 16\frac{1}{6}.

Would you like further clarification or details on any part of the solution?

Here are some related questions you might find helpful:

  1. What is the difference of squares factorization?
  2. How do you find the common denominator for rational expressions?
  3. What are the basic rules for limits involving rational functions?
  4. How do you handle indeterminate forms in limits?
  5. How does factoring help simplify limits?

Tip: Always check for factorizations or common terms that can simplify complex limit expressions.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Calculus
Limits
Algebra
Rational Functions
Difference of Squares

Formulas

Difference of Squares: a^2 - b^2 = (a - b)(a + b)
Limit Evaluation
Simplification of Rational Expressions

Theorems

Difference of Squares
Limit Laws

Suitable Grade Level

Grades 11-12