The general solution of the differential equation $ydx-(x+2y^2)dy = 0$
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → $x = 2y^2+ Cy$, Where C is constant of integration
Given differential equation:
$y\,dx-(x+2y^{2})\,dy=0$
Write in the form:
$y\,dx=(x+2y^{2})\,dy$
Consider $x$ as a function of $y$.
$\frac{dx}{dy}=\frac{x+2y^{2}}{y}$
$\frac{dx}{dy}-\frac{1}{y}x=2y$
This is a linear equation in $x$ with respect to $y$.
Integrating factor:
$IF=e^{\int -\frac{1}{y}dy}=e^{-\log y}=\frac{1}{y}$
Multiply throughout by $\frac{1}{y}$:
$\frac{1}{y}\frac{dx}{dy}-\frac{1}{y^{2}}x=2$
$\frac{d}{dy}\left(\frac{x}{y}\right)=2$
Integrate:
$\frac{x}{y}=2y+C$
$x=2y^{2}+Cy$
Final answer: $x=2y^{2}+Cy$