Answer:
[tex] \cos( {x}^{2}y ) = {y}^{2} \\ \frac{d( \cos( {x}^{2}y) ) }{dx} = \frac{d( {y}^{2}) }{dx} \\ (2xy + {x}^{2} \frac{dy}{dx} ).( - \sin( {x}^{2} y) ) = 2y \frac{dy}{dx} \\ \frac{- 2xy \sin( {x}^{2}y ) - {x}^{2} \sin( {x}^{2} y) }{2y} = \frac{dy}{dx} \\ [/tex]
