Jacobian & Area Calculation of R x D Under T(u,v)

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In summary, the problem involves finding the Jacobian and determining the area of the image D, which is mapped from the given range R = [1, 3] x [1, 4] under the map T(u,v) = (u^2/v, v^2/u). The Jacobian was successfully calculated, but there is confusion on how to find the ranges of u and v since there are no given functions for x and y. It is suggested to solve for u and v using the values in the range of x and y.
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Hashmeer
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Homework Statement


Let D be the image of R = [1; 3] x [1; 4]. under the map
T(u; v) = (u^2/v , v^2/u)

(a) Compute the Jacobian of T.
(b) Compute the area of D.



The Attempt at a Solution


I'm pretty sure I found the Jacobian (I got -2v/u + 2u/v), but I am confused on the next part. How exactly do I find the ranges of u and v since I am not given functions for y and x. Or can I solve the u^2/v and v^2/u for the values in the ranges of x and y to find the ranges for u and v. Thanks for the help.
 
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  • #2
hmm... i would read this as
[tex] (u,v) \in R = [1, 3] \cross [1, 4] [/tex]

T then maps from R into D
[tex] D = T(R) [/tex]
or more explicity
[tex] (s,t) \in D | (s,t) = T(u,v) [/tex]

note i didn't use x & y as i thought they might be confusing the issue
 

1. What is the Jacobian of a transformation?

The Jacobian is a matrix of partial derivatives that represents the rate of change of a transformation at a given point. It is used to calculate the area of a transformed region in a multi-dimensional space.

2. How is the Jacobian related to area calculation?

The Jacobian is used in the formula for calculating the area of a transformed region under a transformation. It is necessary because the transformation may distort the shape and size of the original region, and the Jacobian takes this into account.

3. What is the formula for calculating the Jacobian?

The Jacobian is calculated by taking the determinant of the partial derivative matrix of the transformation. In other words, it is the product of the derivatives of each input variable with respect to each output variable.

4. How is the Jacobian used in coordinate transformations?

In coordinate transformations, the Jacobian is used to convert integrals from one coordinate system to another. It allows us to calculate the area or volume of a region in a new coordinate system, even if the shape and size of the region change.

5. Can the Jacobian be negative?

Yes, the Jacobian can be negative. This indicates that the transformation is orientation-reversing, meaning it changes the direction of the coordinate axes. In this case, the absolute value of the Jacobian is used in the area calculation to ensure a positive result.

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