Change of variables for double integrals

In summary, to find the area of the region R bounded by the given equations, you can use the inverse transformations u=y/x^2 and v=yx^(-1/2) to set up the bounds of the region and then calculate the area.
  • #1
jonnyboy
18
0

Homework Statement


Use a suitable change of variable to find the area of the region R bounded by [tex] y=x^2, y=4x^2, y=\sqrt{x}, y=\frac{1}{2}\sqrt{x}[/tex]


2. The attempt at a solution
I am trying to first find the inverse transformations {u & v =?
 
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  • #2
jonnyboy said:

Homework Statement


Use a suitable change of variable to find the area of the region R bounded by [tex] y=x^2, y=4x^2, y=\sqrt{x}, y=\frac{1}{2}\sqrt{x}[/tex]


2. The attempt at a solution
I am trying to first find the inverse transformations {u & v =?
The obvious thing to do would be to set y= ux2 and y= v[itex]\sqrt{x}[/itex]= vx1/2. That way, R is bounded by u= 1, u= 4, v= 1 and v= 1/2. u= y/x2 and v= yx-1/2.
 

1. What is a change of variables in double integrals?

A change of variables in double integrals is a method used to simplify the evaluation of an integral by transforming the original variables into new variables. This is often done to make the integral easier to solve or to change the region of integration.

2. How is a change of variables done in double integrals?

A change of variables in double integrals involves substituting the original variables with new variables, and then expressing the integral in terms of the new variables. This requires finding the Jacobian of the transformation, which is a function that relates the new variables to the original variables.

3. What is the purpose of a change of variables in double integrals?

The purpose of a change of variables in double integrals is to simplify the evaluation of the integral. This can be done by making the integral easier to solve, or by changing the region of integration to one that is easier to work with.

4. What are some common examples of using a change of variables in double integrals?

Some common examples of using a change of variables in double integrals include changing from rectangular to polar coordinates, or from Cartesian to cylindrical or spherical coordinates. This is often done to solve integrals involving circular, spherical, or other curvilinear regions.

5. Are there any limitations to using a change of variables in double integrals?

Yes, there are some limitations to using a change of variables in double integrals. The transformation must be one-to-one and have a continuously differentiable inverse. Additionally, the region of integration must also be transformed correctly in order to accurately evaluate the integral.

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