How to evaluate this double integral?

This should allow you to use the substitution rule by getting a form of \int y*\sin(\pi y^2) dy.In summary, the problem involves finding the integral of sin(pi*y^2) over the region bounded by x=0, x=2, y=x/4, and y=1/2. Switching the order of integration and using the substitution rule should allow for a solution.
  • #1
Kuma
134
0

Homework Statement



∫0 to 2 ∫x/4 to 1/2 (sin (pi*y2)) dy dx

Homework Equations





The Attempt at a Solution



I think I have to convert this to polar or do some sort of change of variable.

Although in polar y = r sin θ, so then you would have sin of a sin??
 
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  • #2
Try drawing the region and switching the order of integration, and this might allow you to use substitution rule hopefully, as I believe you will get something of the form [itex] \int y*\sin(\pi y^2) dy [/itex]
 
  • #3
Kuma said:

Homework Statement



∫0 to 2 ∫x/4 to 1/2 (sin (pi*y2)) dy dx

Homework Equations





The Attempt at a Solution



I think I have to convert this to polar or do some sort of change of variable.

Although in polar y = r sin θ, so then you would have sin of a sin??

Sketch the region (in the xy-plane) over which the integration is being done. Use this to switch the order of integration.
 

Related to How to evaluate this double integral?

1. What is a double integral?

A double integral is a mathematical concept used to calculate the area under a two-dimensional surface or volume between two variables. It is represented by ∬f(x,y) dA, where f(x,y) is the function being integrated and dA represents the infinitesimal area element.

2. How do I evaluate a double integral?

To evaluate a double integral, you must first determine the limits of integration for both variables. Then, you can use various integration techniques such as substitution, u-substitution, or integration by parts to solve the integral. Once you have solved the integral, you can calculate the numerical value of the double integral.

3. What are the applications of double integrals?

Double integrals have numerous applications in various fields such as physics, engineering, economics, and statistics. They can be used to calculate the volume under a 3D surface, find the mass of an object with varying density, calculate the center of mass, and solve various optimization problems.

4. Can a double integral have a negative value?

Yes, a double integral can have a negative value. This can occur when the function being integrated has negative values within the region of integration. It is important to pay attention to the signs of the function and the limits of integration when evaluating a double integral.

5. What is the difference between a definite and indefinite double integral?

A definite double integral has specific limits of integration and yields a numerical value, while an indefinite double integral does not have any limits of integration and results in a function of two variables. In other words, a definite double integral gives a specific answer, while an indefinite double integral gives a general formula.

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