μr=1−Xm\mu_{r}=1-X_{m}μr=1−Xm
μr=1+Xm\mu_{r}=1+X_{m}μr=1+Xm
μr=3(1+Xm)\mu_{r}=3\left(1+X_{m}\right)μr=3(1+Xm)
μr=1−2Xm\mu_{r}=1-2 X_{m}μr=1−2Xm