Question

有一边长为a的正方形铁皮,将其四个角各截去边长为x的小正方形,然后折成一个无盖的盒子,问小正方形的边长

Answer 1

铁盒的容积为

V = (a - 2x)²x

令V' = -2x(a - 2x) +(a - 2x)² = 0得,x = a/2或a/6

经判断,当x = a/6时,V有最大值