  When a thermally isolated system performs a driving process in the
quasistatic regime, its variation of average work $\langle W\rangle$ is equal
to its quasistatic work $\langle W_{\rm qs}\rangle$. Even though presenting
this simple definition, few attempts have been made to describe such
equilibrium quantity from the fluctuation theorem point of view. In this work,
based on Jarzynski's equality, four forms of such equality are deduced. To
corroborate the results, a relation with the strong inequality $\langle
W\rangle\ge \langle W_{\rm qs}\rangle$ is pursued. It is concluded that any of
the fluctuation theorems deduced cannot derive such a postulate. Also, no
contradiction is observed if the strong inequality is broken down. Based then
on violations for systems starting in the microcanonical ensemble, a
counter-example to the strong inequality at initial low temperature is
presented.
