=\(\frac{-\left(\sqrt{x+1}-\sqrt{x-1}\right)'}{\left(\sqrt{x+1}-\sqrt{x-1}\right)^2}=\frac{-\left(\frac{1}{2\sqrt{x+1}}-\frac{1}{2\sqrt{x-1}}\right)}{-2\sqrt{x+1}\sqrt{x-1}}=\frac{\sqrt{x-1}-\sqrt{x+1}}{4x^2-4}=\frac{1}{4\sqrt{x+1}}-\frac{1}{4\sqrt{x-1}}\)