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lim x → 1 x − 1 √ x 2 + 3 − 2

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Question

\[\lim_{x \to 1} \frac{x - 1}{\sqrt{x^2 + 3 - 2}}\] 

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Solution

\[\lim_{x \to 1} \left[ \frac{x - 1}{\sqrt{x^2 + 3} - 2} \right]\] It is of the form \[\frac{0}{0}\] 

Rationalising the denominator: 

\[\lim_{x \to 1} \left[ \frac{\left( x - 1 \right)\left( \sqrt{x^2 + 3} + 2 \right)}{\left( \sqrt{x^2 + 3} - 2 \right)\left( \sqrt{x^2 + 3} + 2 \right)} \right]\] 

=  \[\lim_{x \to 1} \left[ \frac{\left( x - 1 \right)\left( \sqrt{x^2 + 3} + 2 \right)}{x^2 + 3 - 4} \right]\] 

=  \[\lim_{x \to 1} \left[ \frac{\left( x - 1 \right)\left( \sqrt{x^2 + 3} + 2 \right)}{\left( x^2 - 1 \right)} \right]\] =  \[\lim_{x \to 1} \left[ \frac{\left( x - 1 \right)\left( \sqrt{x^2 + 3} + 2 \right)}{\left( x - 1 \right)\left( x + 1 \right)} \right]\]

= \[\frac{\sqrt{1 + 3} + 2}{1 + 1}\] 

= \[\frac{4}{2}\] 

= 2 

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Chapter 29: Limits - Exercise 29.4 [Page 28]

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R.D. Sharma Mathematics [English] Class 11
Chapter 29 Limits
Exercise 29.4 | Q 9 | Page 28

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