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Question in orthogonal trajectories

  1. Feb 23, 2013 #1

    answer b

    I forget first step

    2aydy/dx = 3x^2

    please can check my answer
  2. jcsd
  3. Feb 23, 2013 #2


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    I'm not able to follow the logic of your method, but it does not seem to give a valid answer. The original family is g(x, y) = x3/y2 = a; if your answer f(x, y) = y2+x = c is correct then you should find ∇f.∇g = 0. ∇g = (3x2/y2, -2x3/y3); ∇f = (1, 2y); ∇f.∇g = 3x2/y2 - 4x3/y2.
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