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Lim X → 0 √ 1 + X + X 2 − 1 X

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Question

\[\lim_{x \to 0} \frac{\sqrt{1 + x + x^2} - 1}{x}\]

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Solution

\[\lim_{x \to 0} \left[ \frac{\sqrt{1 + x + x^2} - 1}{x} \right]\] 

When x = 0, the expression \[\frac{\sqrt{1 + x + x^2} - 1}{x}\] takes the form\[\frac{0}{0}\]

Rationalising the numerator: 

\[\lim_{x \to 0} \left[ \frac{\left( \sqrt{1 + x + x^2} - 1 \right)\left( \sqrt{1 + x + x^2} + 1 \right)}{x\left( \sqrt{1 + x + x^2} + 1 \right)} \right]\]
\[ = \lim_{x \to 0} \left[ \frac{1 + x + x^2 - 1}{x\left( \sqrt{1 + x + x^2} + 1 \right)} \right]\]
\[ = \lim_{x \to 0} \left[ \frac{x\left( 1 + x \right)}{x\left( \sqrt{1 + x + x^2} + 1 \right)} \right]\]
\[ = \frac{1 + 0}{\sqrt{1 + 0 + 0} + 1}\]
\[ = \frac{1}{2}\] 

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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 1 | Page 28

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