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**noteiler** can someone here help me out with an idea how to solve this DE :

$\displaystyle 2xyy' - x^2y'^2 - y^2 = 2S$

S is real constant. i know that this is DE that cannot be solved according to derivative, or it is but if i solved it, i mean if i write it down this way :

$\displaystyle y'=F(x,y)$

i think it would be impossible to solve it, but this DE can't be written down in form $\displaystyle y=F(x,y') or x=F(y,y')$ easily either. of course i can try to solve it some of thease ways, but maybe there is some trick hiding here?