Math Problem Statement

solve

lim(x -> -infinity) e^(2x)(x^2 - 2)

Solution

Let's solve the given limit problem:

limxe2x(x22).\lim_{x \to -\infty} e^{2x}(x^2 - 2).

Step 1: Analyze the terms

  • The exponential term e2xe^{2x} rapidly approaches 0 as xx \to -\infty, because 2x2x \to -\infty.
  • The polynomial term (x22)(x^2 - 2) grows indefinitely large in magnitude (because x2x^2 \to \infty as xx \to -\infty).

Thus, the product e2x(x22)e^{2x}(x^2 - 2) involves a rapidly vanishing exponential term multiplied by a rapidly growing polynomial.

Step 2: Simplify using the exponential dominance property

Exponential terms like e2xe^{2x} approach 0 faster than any polynomial term grows. Thus, regardless of how fast (x22)(x^2 - 2) grows, the factor e2x0e^{2x} \to 0 dominates and forces the product to 0.

Step 3: Conclusion

limxe2x(x22)=0.\lim_{x \to -\infty} e^{2x}(x^2 - 2) = 0.

Let me know if you’d like further clarification or detailed steps!


Here are 5 related questions for practice:

  1. limxex(x2+3)\lim_{x \to \infty} e^{-x}(x^2 + 3)
  2. limxe3x(x3x)\lim_{x \to -\infty} e^{-3x}(x^3 - x)
  3. Evaluate limxe2x/(x2+1)\lim_{x \to \infty} e^{2x}/(x^2 + 1)
  4. Prove that eaxe^{ax} dominates xnx^n as xx \to -\infty (for a<0a < 0).
  5. Evaluate limxex(x5)\lim_{x \to -\infty} e^{x}(x - 5).

Tip: Exponential terms dominate over polynomials at extremes (positive or negative infinity).

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Math Problem Analysis

Mathematical Concepts

Exponential Functions
Limits
Polynomial Growth
Exponential Dominance

Formulas

lim(x -> a) f(x) = L

Theorems

Exponential Dominance Theorem: Exponential decay dominates polynomial growth as x approaches -infinity

Suitable Grade Level

Grades 11-12