Ответ:
\[y=\frac12(x^2+1)^{1/2}x^{-2}.\]
\[y'=\frac{x}{2x^2\sqrt{x^2+1}}-\frac{\sqrt{x^2+1}}{x^3}=-\frac{x^2+2}{2x^3\sqrt{x^2+1}}.\]
Ответ: \(y'=-\frac{x^2+2}{2x^3\sqrt{x^2+1}}\).
\[y=\frac12(x^2+1)^{1/2}x^{-2}.\]
\[y'=\frac{x}{2x^2\sqrt{x^2+1}}-\frac{\sqrt{x^2+1}}{x^3}=-\frac{x^2+2}{2x^3\sqrt{x^2+1}}.\]
Ответ: \(y'=-\frac{x^2+2}{2x^3\sqrt{x^2+1}}\).