2 T2k\frac{2 \mathrm{~T}^{2}}{\mathrm{k}}k2 T2
T22k\frac{\mathrm{T}^{2}}{2 \mathrm{k}}2kT2
T22x\frac{T^{2}}{2 x}2xT2
2kT2\frac{2 \mathrm{k}}{\mathrm{T}^{2}}T22k