2+x21+x2\sqrt{\frac{2+x^{2}}{1+x^{2}}}1+x22+x2
1+x22+x2\sqrt{\frac{1+x^{2}}{2+x^{2}}}2+x21+x2
1+x1−x\sqrt{\frac{1+x}{1-x}}1−x1+x
1+x1+2x\sqrt{\frac{1+x}{1+2 x}}1+2x1+x