If m and n are order and degree of the equation $(\frac{d^2y}{dx^2})^3+4.\frac{(\frac{d^2y}{dx^2})^3}{\frac{d^3y}{dx^3}}+\frac{d^3y}{dx^3}=x^2-1$ then:

m = 3, n = 2

All power of derivative term are rational.        

So, $(\frac{d^3y}{dx^3})(\frac{d^2y}{dx^2})^3+4(\frac{d^2y}{dx^2})^3+(\frac{d^3y}{dx^3})^2=(x^2-1)\frac{d^3y}{dx^3}⇒m = 3,n=2$