Exponential vs Polynomial Growth

3
advanced-math

Which function grows faster as xx \to \infty?

A: f(x)=100x2f(x) = 100x^2B: g(x)=exg(x) = e^x

A

Function B (exponential)

B

Function A (polynomial)

C

They grow at the same rate

D

Cannot determine

Correct Answer: A

Choice A is the correct answer. Exponential always beats polynomial long-term.

  1. Fundamental fact: For any polynomial xnx^n and any exponential axa^x (where a>1a > 1), exponential eventually dominates.
  2. Comparison: As xx \to \infty, exe^x grows much faster than 100x2100x^2.
  3. Example: At x=20x=20, 100(400)=40,000100(400) = 40,000 but e20485,165,195e^{20} \approx 485,165,195.

💡 Strategic Tip: Exponential > Polynomial > Logarithmic (long-term growth rates).

Choice B is incorrect because polynomials grow slower than exponentials. Choice C is incorrect because they have fundamentally different growth rates. Choice D is incorrect because we can definitively determine this.