Math Problem Statement

does the corresponding limit exist? lim (x approaching infinity) (x +2)sin(1/(x-8)

Solution

To evaluate the limit:

limx(x+2)sin(1x8)\lim_{{x \to \infty}} (x + 2) \sin\left(\frac{1}{x - 8}\right)

Let's break this down step by step.

Step 1: Behavior of sin(1x8)\sin\left(\frac{1}{x - 8}\right)

As xx \to \infty, 1x8\frac{1}{x - 8} approaches 00, and since sin(z)z\sin(z) \approx z for small zz, we have:

sin(1x8)1x8asx\sin\left(\frac{1}{x - 8}\right) \approx \frac{1}{x - 8} \quad \text{as} \quad x \to \infty

So, for very large xx, we can approximate:

sin(1x8)1x\sin\left(\frac{1}{x - 8}\right) \approx \frac{1}{x}

Step 2: Behavior of (x+2)sin(1x8)(x + 2) \sin\left(\frac{1}{x - 8}\right)

Now, substituting the approximation sin(1x8)1x\sin\left(\frac{1}{x - 8}\right) \approx \frac{1}{x}, we get:

(x+2)sin(1x8)(x+2)1x(x + 2) \sin\left(\frac{1}{x - 8}\right) \approx (x + 2) \cdot \frac{1}{x}

This simplifies to:

(x+2)1x=1+2x(x + 2) \cdot \frac{1}{x} = 1 + \frac{2}{x}

As xx \to \infty, 2x0\frac{2}{x} \to 0, so the expression tends to:

1+0=11 + 0 = 1

Conclusion:

The limit exists and is equal to 1.

limx(x+2)sin(1x8)=1\lim_{{x \to \infty}} (x + 2) \sin\left(\frac{1}{x - 8}\right) = 1

Do you want further details or have any questions?

Here are 5 related questions:

  1. How does the small angle approximation of sine work for limits?
  2. What happens if the sine function argument does not approach zero?
  3. How do we approach limits that involve both trigonometric functions and polynomial growth?
  4. What are the techniques to simplify limits involving infinity?
  5. Can we solve this limit without using approximations?

Tip: When handling limits involving trigonometric functions, approximations like sin(x)x\sin(x) \approx x for small xx can simplify the process.

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Math Problem Analysis

Mathematical Concepts

Limits
Trigonometric Functions
Small Angle Approximation

Formulas

lim (x → ∞) (x + 2) sin(1/(x - 8))
sin(x) ≈ x for small x

Theorems

Small Angle Approximation Theorem

Suitable Grade Level

Grades 11-12