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Homework Help: Evaluate the line integral

  1. Feb 5, 2012 #1
    1. The problem statement, all variables and given/known data

    Evaluate the line integral ∫c y2 dx + 2xy dy,

    where C, is the path from (1, 2) to (2, 4) parametrised by

    r(t) = (t2 + 1)i + (2t2 + 2)j , 0 ≤ t ≤ 1

    2. Relevant equations

    I worked out the velocity magnitude |v(t)| as 2t√5

    3. The attempt at a solution

    I simply integrated the velocity with respect to t from 0 to 1. and got 56, but then I don't see why I needed that first equation. Are we supposed to do dot product or something first?
  2. jcsd
  3. Feb 5, 2012 #2


    Staff: Mentor

    Aren't you supposed to get x( t) and y(t) from the 2nd eqn and to then sub it into the 1st to convert it to an integral in t from 0 to 1? And then solve it.
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