Math Problem Statement

Use the Squeeze Theorem to evaluate the limit: lim(x → 0) x cos(3/x).

Solution

To evaluate the limit limx0xcos(3/x)\lim_{x \to 0} x \cos(3/x) using the Squeeze Theorem, we proceed as follows:

  1. Understanding the Function: The function of interest is xcos(3/x)x \cos(3/x).

  2. Behavior of cos(3/x)\cos(3/x): We know that cos(3/x)\cos(3/x) oscillates between -1 and 1 for all values of xx except x=0x = 0.

  3. Applying Bounds: 1cos(3/x)1-1 \leq \cos(3/x) \leq 1 Multiplying each part of the inequality by xx (and noting the change of signs if xx is negative), we obtain: xxcos(3/x)x-x \leq x \cos(3/x) \leq x

  4. Limits of the Bounding Functions:

    • As x0x \to 0, both xx and x-x approach 0.
  5. Applying the Squeeze Theorem: Since xxcos(3/x)x-x \leq x \cos(3/x) \leq x and both x-x and xx approach 0 as x0x \to 0, it follows by the Squeeze Theorem that: limx0xcos(3/x)=0\lim_{x \to 0} x \cos(3/x) = 0

Hence, the limit of xcos(3/x)x \cos(3/x) as x0x \to 0 is 0.

Would you like more details on any part of this explanation or have any other questions?

Here are some follow-up topics you might find interesting:

  1. What would change if the limit xax \to a for some a0a \neq 0?
  2. How does the Squeeze Theorem apply to limits involving trigonometric functions generally?
  3. Could we use another method to solve this limit?
  4. What happens to the limit if the function inside the cosine is different, like cos(5/x)\cos(5/x)?
  5. How do we rigorously prove that the function cos(3/x)\cos(3/x) stays within -1 and 1?

Tip: When applying the Squeeze Theorem, it's crucial to ensure the function in question is indeed "squeezed" by the bounding functions at the limit point.

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Math Problem Analysis

Mathematical Concepts

Calculus
Limits
Trigonometric Functions

Formulas

Limit of a function
Trigonometric bounds: -1 ≤ cos(θ) ≤ 1

Theorems

Squeeze Theorem

Suitable Grade Level

Grades 11-12 (High School Calculus)