Math Problem Statement

Find the limit L (if it exists). If it does not exist, explain why. (If an answer does not exist, enter DNE.) lim x → 8⁻ (x - 8) / (x^2 - 64)

Solution

Let's solve the given limit problem step by step.

We are tasked with finding the limit:

limx8x8x264\lim_{{x \to 8^-}} \frac{{x - 8}}{{x^2 - 64}}

Step 1: Simplify the expression.

We start by recognizing that the denominator x264x^2 - 64 is a difference of squares: x264=(x8)(x+8)x^2 - 64 = (x - 8)(x + 8)

So, the expression becomes: x8(x8)(x+8)\frac{{x - 8}}{{(x - 8)(x + 8)}}

Step 2: Cancel common factors.

For x8x \neq 8, we can cancel the common factor of x8x - 8 in the numerator and denominator: 1x+8\frac{{1}}{{x + 8}}

Step 3: Evaluate the limit.

Now, we can directly substitute x=8x = 8 into the simplified expression: limx81x+8=18+8=116\lim_{{x \to 8^-}} \frac{1}{x + 8} = \frac{1}{8 + 8} = \frac{1}{16}

Final Answer:

The limit is 116\frac{1}{16}.


Do you need further details or explanations?

Here are 5 related questions for practice:

  1. How would you compute the limit as x8+x \to 8^+?
  2. What happens if you try to calculate the limit as x8x \to 8 without simplifying the expression?
  3. How does the concept of factoring help in simplifying limits with indeterminate forms?
  4. Can you explain why direct substitution initially leads to an indeterminate form in this case?
  5. How does this example illustrate the difference between one-sided and two-sided limits?

Tip: Always check for factorable expressions in limits that result in indeterminate forms like 00\frac{0}{0}. Simplification often resolves the indeterminacy.

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Math Problem Analysis

Mathematical Concepts

Limits
Factoring
Difference of Squares
One-Sided Limits

Formulas

(x^2 - 64) = (x - 8)(x + 8)
Limit evaluation by simplification

Theorems

Factoring Theorem for Quadratic Differences
Limit Evaluation Rules

Suitable Grade Level

Grade 12, First-Year Calculus