Math Problem Statement

Use the Squeeze Theorem to evaluate \( \lim_{{x \to 0^+}} x \left( 1 - \cos \left( \frac{1}{x} \right) \right) \).

Solution

We are asked to evaluate the limit:

limx0+x(1cos(1x))\lim_{{x \to 0^+}} x \left( 1 - \cos \left( \frac{1}{x} \right) \right)

using the Squeeze Theorem. Let's work through this step-by-step.

Step 1: Analyze the function

The term we are interested in is:

1cos(1x)1 - \cos \left( \frac{1}{x} \right)

We know that the cosine function oscillates between -1 and 1 for any real input, so:

1cos(1x)1-1 \leq \cos \left( \frac{1}{x} \right) \leq 1

From this, we subtract cos(1x)\cos \left( \frac{1}{x} \right) from 1:

01cos(1x)20 \leq 1 - \cos \left( \frac{1}{x} \right) \leq 2

Thus, the term 1cos(1x)1 - \cos \left( \frac{1}{x} \right) is bounded by 0 and 2:

01cos(1x)20 \leq 1 - \cos \left( \frac{1}{x} \right) \leq 2

Step 2: Multiply by xx

Now we multiply the inequality by xx (since x>0x > 0 as x0+x \to 0^+):

0x(1cos(1x))2x0 \leq x \left( 1 - \cos \left( \frac{1}{x} \right) \right) \leq 2x

Step 3: Apply the limit using the Squeeze Theorem

We now apply the limit to the inequality. As x0+x \to 0^+:

\quad \text{and} \quad \lim_{{x \to 0^+}} 2x = 0$$ By the **Squeeze Theorem**, since: $$0 \leq x \left( 1 - \cos \left( \frac{1}{x} \right) \right) \leq 2x$$ and both the upper and lower bounds tend to 0 as $$x \to 0^+$$, we conclude: $$\lim_{{x \to 0^+}} x \left( 1 - \cos \left( \frac{1}{x} \right) \right) = 0$$ ### Final Answer: $$\lim_{{x \to 0^+}} x \left( 1 - \cos \left( \frac{1}{x} \right) \right) = 0$$ Would you like more details on any part of this solution? Here are some related questions for further exploration: 1. How does the Squeeze Theorem work in general for oscillating functions? 2. What other types of limits can the Squeeze Theorem be used to solve? 3. Can you provide an example where the cosine function is used in a different type of limit? 4. How does the cosine function's behavior influence limits like this? 5. What are some examples of limits where the Squeeze Theorem cannot be used? **Tip:** When dealing with oscillatory functions like sine or cosine, always consider their range to see if the Squeeze Theorem can help evaluate limits.

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Math Problem Analysis

Mathematical Concepts

Limits
Oscillating Functions
Trigonometric Functions

Formulas

-

Theorems

Squeeze Theorem

Suitable Grade Level

Grades 11-12