625(1-25%)(1+6%)=530
设平均每月应降低x.
530-500(1-x)²=625-500
530-500+1000x-500x²=125
-500x²+1000x=95
x²-2x=-0.19
x²-2x+1²=-0.19+1²
(x-1)²=0.81
x-1=±0.9
x1=0.1 x2=1.9(不符合题意,舍去)
∴x=0.1
答两个月平均成本下降10%才能使利润相等
(我要追加分)
625(1-25%)(1+6%)=530
设平均每月应降低x.
530-500(1-x)²=625-500
530-500+1000x-500x²=125
-500x²+1000x=95
x²-2x=-0.19
x²-2x+1²=-0.19+1²
(x-1)²=0.81
x-1=±0.9
x1=0.1 x2=1.9(不符合题意,舍去)
∴x=0.1
答两个月平均成本下降10%才能使利润相等
(我要追加分)