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Lim X → ∞ √ X + 1 − √ X

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Question

\[\lim_{x \to \infty} \sqrt{x + 1} - \sqrt{x}\] 

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Solution

\[\lim_{x \to \infty} \left( \sqrt{x + 1} - \sqrt{x} \right)\] 

It is of the form ∞–​​∞.

On rationalising, we get: 

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

 

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Chapter 29: Limits - Exercise 29.6 [Page 38]

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R.D. Sharma Mathematics [English] Class 11
Chapter 29 Limits
Exercise 29.6 | Q 5 | Page 38

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