Show that the change in temperature during throttling of such a gas from an initial pressure P1 to a final pressure P2

Question

The equation of state of a certain gas is v = RT/P + K/RT (where K is a constant). Show that the change in temperature during throttling (enthalpy before and after remaining the same) of such a gas from an initial pressure P₁ to a final pressure P₂ is given by

Where C_p is assumed constant during the process 1 – 2.