Question 978174
The folded up flaps form a 3 cm height.
Let x be the original edge length of the square material.


Base of the box has area  {{{(x-2*3)^2}}}.
Volume, {{{highlight(x(x-2*3)^2=576)}}}.



You would simplify that and put into general form, and then look for roots according to Rational Roots Theorem.  You are only interested in testing the POSITIVE roots.


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