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Exercise 14

Avg difficulty 2.5

Recall we say that function gg dominates function ff provided that lim⁡x→∞f(x)=∞\lim_{x \to \infty} f(x) = \infty, lim⁡x→∞g(x)=∞\lim_{x \to \infty} g(x) = \infty, and lim⁡x→∞f(x)g(x)=0\lim_{x \to \infty} \frac{f(x)}{g(x)} = 0.

  1. Which function dominates the other: ln⁡(x)\ln(x) or x\sqrt{x}?

  2. Which function dominates the other: ln⁡(x)\ln(x) or xn\sqrt[n]{x}? (nn can be any positive integer)

  3. Explain why exe^x will dominate any polynomial function.

  4. Explain why xnx^n will dominate ln⁡(x)\ln(x) for any positive integer nn.

  5. Give any example of two nonlinear functions such that neither dominates the other.

Boelkins, Active Calculus, §3.2 Using derivatives to evaluate limits, Exercise 14

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Adapted from Active Calculus © 2012–2025 Matthew Boelkins. Licensed under CC BY-SA 4.0. Source: Active Calculus. Imported at revision dc86ba3.