(a) If $y\sqrt{x^2+1} = \log\sqrt{x^2+1}-x$, show that $(x^2+1)\frac{dy}{dx} + xy + 1 = 0$. OR (b) Find the differential of $x^{\cot x} + \frac{2x^2-3}{2x^2-x+2}$ with respect to x.