Functions Question 173

Question: $ \underset{x\to \infty }{\mathop{\lim }},[ \sqrt{x+\sqrt{x+\sqrt{x}}}-\sqrt{x} ] $ is equal to

Options:

A) 0

B) $ \frac{1}{2} $

C) $ \frac{1}{p}-\frac{1}{p-1} $

D) $ e^{4} $

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Answer:

Correct Answer: B

Solution:

$ \underset{x\to \infty }{\mathop{\lim }}[ \sqrt{x+\sqrt{x+\sqrt{x}}}-\sqrt{x} ]=\underset{x\to \infty }{\mathop{\lim }},\frac{x+\sqrt{x+\sqrt{x}}-x}{\sqrt{x+\sqrt{x+\sqrt{x}}}+\sqrt{x}} $ $ =\underset{x\to \infty }{\mathop{\lim }},\frac{\sqrt{x+\sqrt{x}}}{\sqrt{x+\sqrt{x+\sqrt{x}}}+\sqrt{x}}=\underset{x\to \infty }{\mathop{\lim }}\frac{\sqrt{1+{x^{-1/2}}}}{\sqrt{1+\sqrt{{x^{-1}}+{x^{-3/2}}}}+1}=\frac{1}{2} $ .