Math Problem Statement

Find the limit: lim (x -> 1/2) (4x^2 - 1) / (x - 1/2)

Solution

The given problem is to solve the limit:

limx124x21x12.\lim_{{x \to \frac{1}{2}}} \frac{4x^2 - 1}{x - \frac{1}{2}}.

Step-by-Step Solution:

  1. Substitution Check: First, let's directly substitute x=12x = \frac{1}{2} into the expression:

    4(12)21=4141=11=0.4\left(\frac{1}{2}\right)^2 - 1 = 4 \cdot \frac{1}{4} - 1 = 1 - 1 = 0.

    The denominator: x12=1212=0.x - \frac{1}{2} = \frac{1}{2} - \frac{1}{2} = 0.

    This gives a 00\frac{0}{0} indeterminate form, so we need to simplify the expression further.

  2. Factorization: The numerator 4x214x^2 - 1 can be factored as a difference of squares: 4x21=(2x1)(2x+1).4x^2 - 1 = (2x - 1)(2x + 1).

    The limit now becomes: limx12(2x1)(2x+1)x12.\lim_{{x \to \frac{1}{2}}} \frac{(2x - 1)(2x + 1)}{x - \frac{1}{2}}.

  3. Cancelation: Notice that x12x - \frac{1}{2} is the same as 2x12x - 1, so we can cancel the common term from the numerator and denominator: limx12(2x1)(2x+1)2x1=limx12(2x+1).\lim_{{x \to \frac{1}{2}}} \frac{(2x - 1)(2x + 1)}{2x - 1} = \lim_{{x \to \frac{1}{2}}} (2x + 1).

  4. Final Substitution: Now substitute x=12x = \frac{1}{2} into the simplified expression: 2(12)+1=1+1=2.2\left(\frac{1}{2}\right) + 1 = 1 + 1 = 2.

Thus, the value of the limit is:

2.\boxed{2}.


Would you like further details or have any questions?

Here are some related questions:

  1. What is L'Hopital's Rule, and how can it help in solving limits with indeterminate forms?
  2. How do you handle limits that result in a 00\frac{0}{0} form?
  3. Can every indeterminate form be simplified through algebraic techniques like factoring?
  4. What is the geometric interpretation of a limit?
  5. How does the concept of continuity relate to limits?

Tip: Always check for factorizations, especially in indeterminate forms, as this often simplifies the limit evaluation.

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Math Problem Analysis

Mathematical Concepts

Limits
Factoring
Indeterminate Forms
Algebra

Formulas

Difference of squares: a^2 - b^2 = (a - b)(a + b)

Theorems

Limit of a function
Factoring to resolve indeterminate forms

Suitable Grade Level

Grade 11-12