The correct answer is \(=3sinxcosx(sinx-2cos^4x)\) Let \(y=sin^3x+cos^6x\) \(∴\frac{dy}{dx}=\frac{d}{dx}(sin^3x)+\frac{d}{dx}(cos^6x)\) \(=3sin^2x.\frac{d}{dx}(sinx)+6cos^5x.\frac{d}{dx}(cosx)\) \(=3sin^2x.cosx+6cos^5x.(-sinx)\) \(=3sinxcosx(sinx-2cos^4x)\)