Q. The differential equation representing the family of curves $y^{2} = 2c(x + c^{\frac{2}{3}})$, where $c$ is a positive parameter, is of

A) Order 3, degree 3
B) Order 2, degree 4
C) Order 1, degree 5
D) Order 5, degree 1
Explanation

(c)
$y^{2} = 2c(x + c^{\frac{2}{3}})$
$\Rightarrow$ $2y\ \frac{dy}{dx} = 2c \Rightarrow c = y\ \frac{dy}{dx}$
$\therefore$ $y^{2} = 2y\ \frac{dy}{dx}\left( x + \left( y\ \frac{dy}{dx} \right)^{\frac{2}{3}} \right)$
$\Rightarrow$ $\left( \frac{y}{2\frac{dy}{dx}} - x \right) = \left( y\ \frac{dy}{dx} \right)^{\frac{2}{3}}$
$\Rightarrow$ $\left( y - 2x\ \frac{dy}{dx} \right)^{3} = \left( 2\ \frac{dy}{dx} \right)^{3}\left( y\ \frac{dy}{dx} \right)^{2}$
$\Rightarrow$ $\left( y - 2x\ \frac{dy}{dx} \right)^{3} = 8y^{2}\left( \frac{dy}{dx} \right)^{5}$
Here, order=1, degree=5

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.