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Lim X → 3 √ X + 3 − √ 6 X 2 − 9 - Mathematics

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Question

\[\lim_{x \to 3} \frac{\sqrt{x + 3} - \sqrt{6}}{x^2 - 9}\] 

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Solution

\[\lim_{x \to 3} \left[ \frac{\sqrt{x + 3} - \sqrt{16}}{x^2 - 9} \right]\] It is of the form \[\frac{0}{0}\] 

Rationalising the numerator: 

\[\lim_{x \to 3} \left[ \frac{\left( \sqrt{x + 3} - \sqrt{6} \right)\left( \sqrt{x + 3} + \sqrt{6} \right)}{\left( x^2 - 9 \right)\left( \sqrt{x + 3} + \sqrt{6} \right)} \right]\] 

= \[\lim_{x \to 3} \left[ \frac{\left( x + 3 - 6 \right)}{\left( x - 3 \right)\left( x + 3 \right)\left( \sqrt{x + 3} + \sqrt{6} \right)} \right]\] 

=  \[\frac{1}{6 \times 2\sqrt{6}}\] 

=  \[\frac{1}{12\sqrt{6}}\] 
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Chapter 29: Limits - Exercise 29.4 [Page 28]

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RD Sharma Mathematics [English] Class 11
Chapter 29 Limits
Exercise 29.4 | Q 10 | Page 28

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