<s>[INST] An open box is constructed from a square piece of cardboard by removing a square from each corner. The area of the interior of the box can be represented by \( A(x) = 4x^2 + 12x \), where \( x \) is the length of the side of the square removed from each corner. Given that \( x > 0 \), find the value of \( x \) that makes the interior area of the box a maximum.[/INST]