Given 2 variable of initial value of Pint*Vint obtain final value of Pfinal*Vfinal after undergo an infinitesimal changes.
If able to find the relationship of equation like below
Pint(Vint)+infinitesimal change=Pfinal(Vfinal)
The equation is solvable to get relationship of dp and dv, integrate the dp and dv on both side will get how Pfinal change with respect to Vfinal irrespective how big the changes?