Maths · The solution of differential equation by the method of separation of variables

d x=x^{2} d y \)

\( \left(1-x y+x^{2} y^{2}\right) d x=x^{2} d y \)

  • A. \( _{y}=\frac{1}{x} \tan (\ln |c y|) \)
  • B. \( _{x}=\frac{1}{y} \tan (\ln |c x|) \)
  • C. \( x=\frac{1}{y} \cot (\ln |c y|) \)
  • D. \( y=\frac{1}{x} \cot (\ln |c x|) \)

Step-by-step solution

Rewrite the differential equation as x d(xy) = (1 + (xy)^2) dx, then separate variables: d(xy)/(1+(xy)^2) = dx/x. Integrate to get arctan(xy) = ln|x| + C, so xy = tan(ln|x|+C). Write C = ln|c| to obtain xy = tan(ln|c x|), which is equivalent to x = (1/y) tan(ln|c x|).
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