Differential Calculus Help?

Question

A rectangle is drawn with its lower vertices on the x axis and its upper vertices on the curve y= e^-2x
Write down an expression for A in terms of x
Find the maximum value of A
Justify your answers in both cases.
Thanks a lot.

Answer 1

Both upper vertices can´t be on y = e^-2x as the line joining them must be parallel to the x axis and a parallel to the x axis
cuts y=e^-2x in only one point
e^-2x = h so x= -l1/2*ln h
Repeat your question