(1+2x)1(1+2 x)^{1}(1+2x)1
(1−2x)−1(1-2 x)^{-1}(1−2x)−1
(1+x)−2(1+x)^{-2}(1+x)−2
(1−x)−2(1-x)^{-2}(1−x)−2