prove or display a desproving example:

A)

there is f and g which are defined for which .

if 0<g(x)<1 for then

B)

if f monotonickly decreasing in and then f(x)>0 for all

C)if f differentiable in (a,b) so then there is so

D)if f is integrabile in [a,b] then there is x in [a,b] so

regarding a:

i dont know from the start how to know intuetivly whether its true or false

?