=-\frac{2x^2-2x\sqrt{1+x^2}+1}{8}+\frac{1}{8}\cdot{\frac{1}{(x-\sqrt{1+x^2})^2}}\cdot{\frac{(x+\sqrt{1+x^2})^2}{(x+\sqrt{1+x^2})^2}}-\frac{1}{2}ln|x-\sqrt{1+x^2}|+C=