Math Problem Statement

\lim_{x\rarr1} $$$$ \frac{\sqrt{x}-1}{x-1}

Solution

The given limit is:

limx1x1x1\lim_{x \to 1} \frac{\sqrt{x} - 1}{x - 1}

Step-by-Step Solution:

  1. Direct Substitution: Plugging x=1x = 1 directly into the expression, we get:

    1111=1111=00\frac{\sqrt{1} - 1}{1 - 1} = \frac{1 - 1}{1 - 1} = \frac{0}{0}

    This is an indeterminate form, so we must simplify the expression further.

  2. Rationalizing the Numerator: To simplify, we can multiply both the numerator and denominator by the conjugate of the numerator, x+1\sqrt{x} + 1:

    x1x1×x+1x+1=(x1)(x+1)(x1)(x+1)\frac{\sqrt{x} - 1}{x - 1} \times \frac{\sqrt{x} + 1}{\sqrt{x} + 1} = \frac{(\sqrt{x} - 1)(\sqrt{x} + 1)}{(x - 1)(\sqrt{x} + 1)}

    The numerator simplifies using the difference of squares:

    (x1)(x+1)=x1(\sqrt{x} - 1)(\sqrt{x} + 1) = x - 1

    So the expression becomes:

    x1(x1)(x+1)\frac{x - 1}{(x - 1)(\sqrt{x} + 1)}

  3. Canceling Terms: Now, we can cancel the x1x - 1 terms from both the numerator and denominator (as long as x1x \neq 1):

    1x+1\frac{1}{\sqrt{x} + 1}

  4. Substitute x=1x = 1: Now that the indeterminate form is resolved, substitute x=1x = 1:

    11+1=11+1=12\frac{1}{\sqrt{1} + 1} = \frac{1}{1 + 1} = \frac{1}{2}

Final Answer:

limx1x1x1=12\lim_{x \to 1} \frac{\sqrt{x} - 1}{x - 1} = \frac{1}{2}

Would you like further clarification or additional details?


Here are 5 related questions to explore further:

  1. How would you handle limits involving cube roots instead of square roots?
  2. What happens when the indeterminate form 00\frac{0}{0} arises in other contexts?
  3. Can you apply L'Hôpital's Rule to solve this limit? How would it work?
  4. How does the process change if the limit is limx0x1x1\lim_{x \to 0} \frac{\sqrt{x} - 1}{x - 1}?
  5. What are the differences between rationalizing the numerator and the denominator in limits?

Tip: Always check for indeterminate forms first to decide the best method for evaluating limits.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Limits
Indeterminate Forms
Rationalization
Square Roots

Formulas

lim_{x→a} (f(x)/g(x))
(sqrt{x} - 1)(sqrt{x} + 1) = x - 1

Theorems

Difference of Squares
Limits and Indeterminate Forms

Suitable Grade Level

Grades 10-12