设第i个月生产xi单位产品,则生产成本费为xi^2元,
xi<=di时仓库存货成本费为0;xi>di时仓库存货成本费为xi-di元,
x1+x2+x3=d1+d2+d3=330,xi>0,
三个月总的生产和存货费用y=x1^2+x2^2+x3^2+x1-d1+x2-d2
=x1^2+x2^2+(330-x1-x2)^2+x1+x2-d1-d2,
=(x1+x2)^2-2x1x2+330^2-660(x1+x2)+(x1+x2)^2+x1+x2-210
=2(x1+x2)^2-659(x1+x2)-2x1x2+330^2-210,
2x1x2<=(x1+x2)^2/2,
所以y>=(3/2)(x+1)^2-659(x1+x2)+330^2-210
=(3/2)(x1+x2-659/3)^2+330^2-659^2/6-210
>=330^2-659^2/6-210≈36309.83,
当x1=x2=659/6时取等号.
可以吗?