#double integrals and jacobian

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quiet turret
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Hello! I need help with a problem I cant solve no matter what I try. Its given to calculate
Double Integral(x^2+y^2)dxdy on area given with equations x^2-y^2=1,4 and xy=1,3 in the first quadrant. There is a hint to use u=xy and v=x^2-y^2 and I don't know how to get the Jacobian to be an actual value not dependent on x or y

prisma vergeBOT
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spark rock
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like the Jacobian for polar coordinates is r, which isnt a number

quiet turret
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Oh yeah but i mean wouldnt I get a Jacobian has x or y in it

spark rock
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no

quiet turret
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But i switch to integration with u v

spark rock
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you have x=g(u,v) and y=h(u,v)

quiet turret
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Yeah but with the substitution u=xy and v=x^2-y^2 im having trouble actually getting those functions

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And valid results to partially derive

spark rock
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$u=xy\to 1 = xy_u+yx_u$ and $v=x^2-y^2\to 0 = 2xx_u-2yy_u$

unkempt portalBOT
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Omegabet_

spark rock
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which is a linear system in $x_u$ and $y_u$

unkempt portalBOT
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Omegabet_

spark rock
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which are the things you want for the jacobian

quiet turret
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Thank youbpanik , would it be too much to explain how you got the second part

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Why is v becoming 0

spark rock
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$\partial_u v=0$

unkempt portalBOT
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Omegabet_

quiet turret
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Okay thank you, I will try to solve with this but may I ask for help if I get stuck sobbingTEArs

quiet turret
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I got it!!! Thank you very much

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They have not mentioned to me once about the inverse of a Jacobian

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And that helped me so much

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Erm