Question 1044299
x  edge of square base
y  height of the open box


{{{x^2y=10}}} accounts for volume.


Amount of material , S,  is sum of all the five surface areas.
{{{4xy+x^2=S}}}


Solve the volume equation for y.
{{{y=10/x^2}}}
Substitute into the S equation.
{{{S=4x(10/x^2)+x^2}}}
Simplify.
{{{S=(40/x+4x^3)}}}
{{{S=40/x+4x^4/x}}}
{{{highlight(S=(40+x^4)/x)}}}