Question

From each corner of a square piece of cardboard, remove a square of sides 3 inch. Turn up the edges to form an open box. If the box is to hold 300 inch cubed, what are the dimensions of the original piece of cardboard?

Answer 1

v = 3(x-6)^2
when v=300, we have (x-6)^2 = 100, so x = 16.