L’Hospital’s Rule and Indeterminate Forms — Question 5

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Question 5

Evaluate the limit: limx→∞ln⁡xx\lim_{x \to \infty} \frac{\ln x}{\sqrt{x}}

Original worksheet page 1: question and worked solution for 4-10-005
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Question 5 - Solution

As x→∞x \to \infty, both numerator and denominator approach infinity: ln⁡xx→∞∞(indeterminate form)\frac{\ln x}{\sqrt{x}} \to \frac{\infty}{\infty} \quad \text{(indeterminate form)}

Apply L’Hospital’s Rule: limx→∞ln⁡xx=limx→∞ddxln⁡xddxx=limx→∞1x12x=limx→∞2xx=limx→∞2x=0\lim_{x \to \infty} \frac{\ln x}{\sqrt{x}} = \lim_{x \to \infty} \frac{\frac{d}{dx} \ln x}{\frac{d}{dx} \sqrt{x}} = \lim_{x \to \infty} \frac{\frac{1}{x}}{\frac{1}{2\sqrt{x}}} = \lim_{x \to \infty} \frac{2\sqrt{x}}{x} = \lim_{x \to \infty} \frac{2}{\sqrt{x}} = 0

Final Answer: 0\boxed{0}

Original worksheet page 2: question and worked solution for 4-10-005

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