✔ 最佳答案
Sol
(1)
設增加x人收入最高
f(x)=(x+26)(4000-100x)
=4000x-100x^2+104000-2600x
=-100x^2+1400x+104000
=-100(x^2-14x)+104000
=-100(x^2-14x+49)+108900
=-100(x-7)^2+108900
(x-7)^>=0
-(x-7)^2<=0
-100(x-7)^2<=0
-100(x-7)^2+108900<=108900
f(x)<=108900
x=7時
增加7人收入最高
(2) 108900元