2x = 10/y^2, So x = 5/y^2
2y - 20/5y^2 = 0
2y - 4/y^2 = 0
y^3 = 2.
Check the simplifications.
i am having trouble getting the correct answer on the following question:
A box open at the top has a volume of . Find the dimensions which give minimum surface area.
sub w into (2) equation
make x the subject of equation (4)
sub back into equation (3)
0 is unrealistic so don't consider it.
my answer m , m, 16m
answer is cubic root 20m, cubic root 20m, 0.5 cubic root 20m