2α.P1−α\frac{2 \alpha . \mathrm{P}}{1-\alpha}1−α2α.P
2α.P1+α\frac{2 \alpha . \mathrm{P}}{1+\alpha}1+α2α.P
α.P1+α\frac{\alpha. P}{1+{\alpha}}1+αα.P
α.P1−α\frac{\alpha . P}{1-\alpha}1−αα.P