If 300 cm2 of material is available to make a box with a square base and an open top, find the maximum volume of the box in cubic centimeters

Check the picture below, recall the base is a square, so each side being equally "x".



now, if you do a first-derivative test on +10, say check 9.99 and 10.01 for example, you'll notice you'd get + and - value respectively, meaning is a maximum.

21/2 or 5/2