Correct option: B.$x y \frac{d^2 y}{d x^2}+2\left(\frac{d y}{d x}\right)^2-y \frac{d y}{d x}=0$
$x y \frac{d^2 y}{d x^2}+2\left(\frac{d y}{d x}\right)^2-y \frac{d y}{d x}=0$Hint: $\frac{x^2}{a^2}-\frac{y^2}{b^2}=1$
... (1)
$\therefore \frac{1}{a^2} \times 2 x-\frac{1}{b^2} \times 2 y \frac{d y}{d x}=0$
$\therefore \frac{x}{a^2}-\frac{y}{b^2} \frac{d y}{d x}=0$
$\ldots$ (2)
and $\frac{1}{a^2} \times 1-\frac{1}{b^2}\left[y \frac{d^2 y}{d x^2}+\left(\frac{d y}{d x}\right)^2\right]=0$
Equations (1), (2) and (3) are consistent
$\therefore\left|\begin{array}{ccc}x^2 & -y^2 & 1 \\ x & -y \frac{d y}{d x} & 0 \\ 1 & -\left[y \frac{d^2 y}{d x^2}+\left(\frac{d y}{d x}\right)^2\right] & 0\end{array}\right|=0$
$\left.\therefore x y \frac{d^2 y}{d x^2}+x\left(\frac{d y}{d x}\right)^2-y \frac{d y}{d x}=0\right]$