(a)
Given, $\left\lbrack 1 + \left( \frac{dy}{dx} \right)^{2} \right\rbrack^{\frac{5}{2}} = \frac{d^{3}y}{dx^{3}}$
$\Rightarrow$ $\left( \frac{d^{3}y}{dx^{3}} \right)^{2} = \left\lbrack 1 + \left( \frac{dy}{dx} \right)^{2} \right\rbrack^{5}$
Here, order=3, degree=2