1+x22x−1\frac{1+x^{2}}{2 x-1}2x−11+x2
2x−11+x2\frac{2 x-1}{1+x^{2}}1+x22x−1
1+x22x+1\frac{1+x^{2}}{2 x+1}2x+11+x2
1−2x1+x2\frac{1-2 x}{1+x^{2}}1+x21−2x