Question 1110914
x, edge length of each square to remove

volume, {{{(5-2x)(8-2x)x}}}


{{{x(40-26x+4x^2)}}}

{{{x(4x^2-26x+40)}}}

{{{4x^3-26x^2+40x}}}


{{{dv/dx=12x^2-52x+40}}}


{{{12x^2-52x+40=0}}}
{{{3x^2-13x+10=0}}}
The root needed is ...

{{{system(x=highlight((13-7)/(2*3)),OR,x=cross((13+7)/(2*3)))}}}