Q. The solution of the differential equation $9y\ \frac{dy}{dx} + 4x = 0$ is
A) $\frac{y^{2}}{9} + \frac{x^{2}}{4} = c$
B) $\frac{y^{2}}{4} + \frac{x^{2}}{9} = c$
C) $\frac{y^{2}}{9} - \frac{x^{2}}{4} = c$
D) $y^{2} - \frac{x^{2}}{9} = c$
Explanation
(b)
Given, $\frac{y}{4}\ dy = - \frac{x}{9}dx$
$\Rightarrow$ $\frac{y^{2}}{4.2} = - \frac{x^{2}}{9.2} + \frac{c}{2}$
$\Rightarrow$ $\frac{y^{2}}{4} + \frac{x^{2}}{9} = c$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.