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Help! Differential Equations types

  1. Feb 19, 2015 #1
    1. The problem statement, all variables and given/known data
    Good day all,

    My professor gave my class a packet of about 40 differential equations.
    I for the life of me cannot figure out how t solve these last 4!
    I also have an exam tomorrow morning, and would like finish these last few.

    I dont need them solved out, I would just like to know what kind they are a maybe a hint to get started on them!
    NOTE: They WILL be one of the following types:

    seperable
    Bernoulli
    Exact
    Linear
    Homogeneous



    2. Relevant equations

    1) (2x+1)dx+((x^(2)-y)/x)dy=0

    2)(cos2y-sinx)dx+(-2tanxsin2y)dy=0

    3)(x^(2)y+xy-y)dx+(x^(2)y-2x^(2))dy=0

    4)dy/dx=(-3x^(2)y-y^(2))/(2x^(3)+3xy)



    3. The attempt at a solution

    I have tried all sorts of ways, some take a page plus. I cant tell of these have obvious solutions or if there is a trick. Im a little worn out after solving 35 of them.
    Any help would be greatly appreciated!
    Thanks!
     
  2. jcsd
  3. Feb 19, 2015 #2
    I think the 3rd one is exact, but I computed the partial derivatives in my head, so double check before you take my word on it.


    Actually nvm I don't think it is.
     
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