Math Problem Statement

integrate sin(x)/x from -1 to 1

Solution

To evaluate the integral 11sin(x)xdx\int_{-1}^{1} \frac{\sin(x)}{x} \, dx, we need to be aware that this integral is a well-known improper integral called the sine integral, denoted as Si(x)\text{Si}(x).

However, directly evaluating it from 1-1 to 11 involves understanding the properties of the sine function and using symmetry.

Given the symmetry of sin(x)\sin(x) around 00, the integral can be split as:

11sin(x)xdx=201sin(x)xdx\int_{-1}^{1} \frac{\sin(x)}{x} \, dx = 2 \int_{0}^{1} \frac{\sin(x)}{x} \, dx

This is because sin(x)x\frac{\sin(x)}{x} is an even function, so the integral from 1-1 to 11 is twice the integral from 00 to 11.

To solve 01sin(x)xdx\int_{0}^{1} \frac{\sin(x)}{x} \, dx, we recognize that this is the definition of the Sine Integral function, Si(x)\text{Si}(x):

Si(x)=0xsin(t)tdt\text{Si}(x) = \int_{0}^{x} \frac{\sin(t)}{t} \, dt

Thus,

01sin(x)xdx=Si(1)\int_{0}^{1} \frac{\sin(x)}{x} \, dx = \text{Si}(1)

The value of Si(1)\text{Si}(1) is a known constant, approximately:

Si(1)0.946083\text{Si}(1) \approx 0.946083

Therefore,

11sin(x)xdx=2Si(1)20.946083=1.892166\int_{-1}^{1} \frac{\sin(x)}{x} \, dx = 2 \cdot \text{Si}(1) \approx 2 \cdot 0.946083 = 1.892166

Thus, the integral evaluates to approximately 1.892166.

Would you like more details or have any questions?

Here are five questions you can ask next:

  1. How do you integrate functions using integration by parts?
  2. What is the process for solving definite integrals?
  3. How do you handle improper integrals?
  4. Can you explain the Sine Integral function in more detail?
  5. What are some common techniques for evaluating difficult integrals?

Tip: When dealing with symmetric integrals, consider whether the function is even or odd to potentially simplify the computation.

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Math Problem Analysis

Mathematical Concepts

Integral Calculus
Improper Integrals
Sine Integral Function

Formulas

Definition of the Sine Integral: Si(x) = \int_{0}^{x} \frac{\sin(t)}{t} \, dt

Theorems

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Suitable Grade Level

Advanced Undergraduate