\(y = ae^{2x} + be^{-2x} + c\)
\(\frac{dy}{dx} = 2ae^{2x} - 2be^{-2x}\)
\(\frac{d^2y}{dx^2} = 4ae^{2x} + 4be^{-2x}\)
\(= 4(ae^{2x} + be^{-2x})\)
\(= 4(y - c)\)
\(= 4y - 4c\)
\(\therefore \frac{d^3y}{dx^3} = 4\frac{dy}{dx}\)
⇒ \(\frac{d^3y}{dx^3} - 4\frac{dy}{dx}=0\)
which is required differential equation.