CHAP. 3: FUNDAMENTALS OF THERMODYNAMICS [CONTENTS] 82
It is often necessary to integrate dzwith one fixed independent variable. For the integration
fromx 1 tox 2 at constantyit applies that
z(x 2 , y) =z(x 1 , y) +
∫x 2
x 1
(
∂z
∂x
)
y
dx , [y]. (3.32)