A gas undergoes a process in which the pressure P and volume V are related as VP2n−1=constant.  Find the bulk modulus for the gas.

V   P2n−1=constant⇒   V2n−1  P2n−2 dP  + P2n−1dV=0⇒   V2n−1  P2n−2 dP  − P2n−1dV⇒  −dPdVV= P2n−12n−1 P2n−2⇒    =    P2n−1−2n+22n−1 =P2n−1