I need the solution to substitute into another equation... which I can do... once I have the solution...

2. " A vase is shaped so that it's cross-sectional area at a height

*h* from its base is:

A=f(h), O \< h \< H

where H is the total height of the vase. The vase is filled to the top with water, which then evaporate at a rate proportional to the surface area so that:

dV/dt= -k*A

where V(t) is the volume of water and A(t) is the surface area at time t. Show that the height of water in the vase obeys a simple eqn of the form

dh/dt=-k , with k as a constant, regardless of what the function f is and hence.... ....."

I don't know where to start with this q, I think you need to change dV so it is in terms of area and height but not sure how to go about it...

Thanks again! x x x