Math Problem Statement

If 4x ≤ g(x) ≤ 2x4 − 2x2 + 4 for all x, evaluate lim x→1 g(x).

Solution

We are given the inequality:

4xg(x)2x42x2+44x \leq g(x) \leq 2x^4 - 2x^2 + 4

We need to evaluate:

limx1g(x)\lim_{x \to 1} g(x)

Step 1: Find the limits of the bounding functions as x1x \to 1

  1. The lower bound is 4x4x, so let's find its limit as x1x \to 1:

limx14x=41=4\lim_{x \to 1} 4x = 4 \cdot 1 = 4

  1. The upper bound is 2x42x2+42x^4 - 2x^2 + 4, so let's compute its limit as x1x \to 1:

limx1(2x42x2+4)=2(1)42(1)2+4=22+4=4\lim_{x \to 1} (2x^4 - 2x^2 + 4) = 2(1)^4 - 2(1)^2 + 4 = 2 - 2 + 4 = 4

Step 2: Apply the Squeeze Theorem

From the inequality 4xg(x)2x42x2+44x \leq g(x) \leq 2x^4 - 2x^2 + 4, and knowing that both the lower bound and upper bound tend to 4 as x1x \to 1, by the Squeeze Theorem, we conclude:

limx1g(x)=4\lim_{x \to 1} g(x) = 4

Conclusion:

4\boxed{4}

Would you like further details or have any questions? Here are some related questions to explore this topic further:

  1. What is the Squeeze Theorem and how does it work?
  2. How would the solution change if the bounds of g(x)g(x) were different?
  3. Can the Squeeze Theorem be applied if the limits of the bounds are not equal?
  4. What is the significance of continuity in using the Squeeze Theorem?
  5. How do you evaluate limits involving polynomials like 2x42x2+42x^4 - 2x^2 + 4?

Tip: The Squeeze Theorem is particularly useful when a function is "trapped" between two other functions that approach the same limit.

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Math Problem Analysis

Mathematical Concepts

Calculus
Limits
Inequalities

Formulas

lim x→1 4x = 4
lim x→1 (2x^4 - 2x^2 + 4) = 4

Theorems

Squeeze Theorem

Suitable Grade Level

Grades 11-12