i have no idea how to get started. pls help.Find the volume of the largest rectangular box in the first octant with three faces in the coordinate planes, and one vertex in the plane . Largest volume is
$\displaystyle V = xyz = 36yz - 4y^2z -9yz^2$
$\displaystyle V_{y} = 36z - 8yz -9z^2 = 0$
$\displaystyle V_{z} = 36y - 4y^2 - 18yz =0$
then solve for y,z and i got
y=0, z=0
y=5/2, z = 16/9
and substitude y and z into V and i got V = 400/9
but it's not the right answer. anything wrong? Please help! due tonight