Math Problem Statement

limit of [{x-√(2-x^2)} / {2x-√(2+2x^)}]

Solution

To evaluate the limit

limx1x2x22x2+2x\lim_{{x \to 1}} \frac{x - \sqrt{2 - x^2}}{2x - \sqrt{2 + 2x}}

we’ll start by directly substituting x=1x = 1 into the expression to see if it results in an indeterminate form:

  1. Substitute x=1x = 1:

    1212212+21=12122+2\frac{1 - \sqrt{2 - 1^2}}{2 \cdot 1 - \sqrt{2 + 2 \cdot 1}} = \frac{1 - \sqrt{2 - 1}}{2 - \sqrt{2 + 2}}

    Simplifying inside the square roots:

    =1124=1122=00= \frac{1 - \sqrt{1}}{2 - \sqrt{4}} = \frac{1 - 1}{2 - 2} = \frac{0}{0}

    This results in the indeterminate form 00\frac{0}{0}, so we need to manipulate the expression further to evaluate the limit.

  2. Rationalize the numerator and denominator:

    To resolve the indeterminate form, we can multiply both the numerator and the denominator by the conjugate expressions of each part.

    Rationalize the numerator: Multiply the numerator and the denominator by the conjugate of x2x2x - \sqrt{2 - x^2}, which is x+2x2x + \sqrt{2 - x^2}:

    (x2x2)(x+2x2)(2x2+2x)(x+2x2)\frac{\left( x - \sqrt{2 - x^2} \right)\left( x + \sqrt{2 - x^2} \right)}{\left( 2x - \sqrt{2 + 2x} \right) \left( x + \sqrt{2 - x^2} \right)}

    This simplifies the numerator to:

    (x)2(2x2)2=x2(2x2)=x22+x2=2x22=2(x21)(x)^2 - ( \sqrt{2 - x^2} )^2 = x^2 - (2 - x^2) = x^2 - 2 + x^2 = 2x^2 - 2 = 2(x^2 - 1)

    Therefore, the expression becomes:

    2(x21)(2x2+2x)(x+2x2)\frac{2(x^2 - 1)}{ \left( 2x - \sqrt{2 + 2x} \right) \left( x + \sqrt{2 - x^2} \right) }

    Notice that x21=(x1)(x+1)x^2 - 1 = (x - 1)(x + 1), so we can rewrite it as:

    2(x1)(x+1)(2x2+2x)(x+2x2)\frac{2(x - 1)(x + 1)}{ \left( 2x - \sqrt{2 + 2x} \right) \left( x + \sqrt{2 - x^2} \right) }

  3. Simplify the expression and apply the limit:

    We can now proceed by further rationalizing the denominator in a similar manner if necessary.

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Math Problem Analysis

Mathematical Concepts

Limits
Indeterminate Forms
Rationalization

Formulas

Limit as x approaches a value
Conjugate method for rationalizing expressions

Theorems

Indeterminate Form 0/0
Limit Laws

Suitable Grade Level

Grade 12 or College-level Calculus