Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Help with Changing of variables, Jacobian, Double Integrals?

  1. Mar 7, 2012 #1


    User Avatar

    1. The problem statement, all variables and given/known data

    Show that T(u,v) = (u2 - v2, 2uv)
    maps to the triangle = {(u,v): 0 ≤ v ≤ u ≤ 4} to the domain D
    bounded by x=0, y=0, and y2 = 1024 - 64x.

    Use T to evaluate ∬D sqrt(x2+y2) dxdy

    2. Relevant equations

    3. The attempt at a solution

    Jacobian= 4u2+4v2 dudv
    I guess the equation in the changed variable integral should be ∫∫sqrt((u2-v2)2+(2uv)2) (4u2+4v2) dudv

    But, I don't know how to get the bounds for the integrals in terms of u and v.
    Can someone help me on this??
  2. jcsd
  3. Mar 7, 2012 #2
    The first part of the problem already told you what the bounds of u and v are
  4. Mar 7, 2012 #3


    User Avatar

    I know that 0 ≤ u ≤ 4 and 0 ≤ v ≤4.
    For y^2 = 1024 - 64x, x is restricted from 0 ≤ x ≤16 and 0 ≤ y ≤32??
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook