A closed rectangular box has a height ycm and width xcm. Its length is twice its width. It has a fixed outer surface area of 300cm^2
A) Show that 4x^2+6xy=300
B) Find an expression for y in terms of x
C) Hence show that the volume V of the box is given by V=100x^4/3x^3
D) Find dV/dX
E) Hence find the value of x and of y required to make the volume of the box maximum
F) Calculate the maximum volume