...mathematical analysis...
suppose (X_1 ,τ_1 ) and (X_2 ,τ_2 )
are two topological spaces.
prove f:(X_1 ,τ_1 )→(X_2 ,τ_2 ) is
a continuous function if only
if for any subset A⊆X_1 :
f(cl(A))⊆cl(f(A))
A mercury based barometer reads
760mmhg at the base of a mountain and
704.0mmhg at the top. Find the height
of the mountain if the density of
mercury and air are respectively
13600kgm^(−3) and 1.25kgm^(−3) (g=10ms^(−2) )