Question

做一個(gè)體積為8m³，底面為正方形的長(zhǎng)方體紙盒，至少需要材料______m²．

Answer 1

設(shè)長(zhǎng)方體紙盒底面正方形邊長(zhǎng)為a，高為h，則a²h=8，h=

8

a2

，
紙盒的表面積為S=4ah+2a²=

32

a

+2a²=

16

a

+

16

a

+2a²=≥3

3	16 a × 16 a ×2a2

=24
當(dāng)且僅當(dāng)

16

a

=2a²，a=2時(shí)取等號(hào)
故答案為：24