Question 1036451
The base and the height give the volume function which has been done and simplified for you, as {{{V(x)=4x^3-164x^2+1600x=3600}}}; and you just need to solve for x, using the simplified....., {{{4x^3-164x^2+1600x-3600=0}}},
{{{highlight_green(x^3-41x^2+400x-900=0)}}}.


Find the zeros or roots.  One of them will be the cut value of the square corner to remove to form the box.