Y=20-0.8*(X-100)/10=28-0.08X 100<=X<=200
Y=20-0.8*(200-100)/10-1*(X-200)/10=32-0.1X X>200
W=X*Y-40Y-480-1520=X*Y-40Y-2000
=-0.08X^2+31.2X-3120 100<=X<=200
=-0.1X^2+36X-3280 X>200
W<0恒成立,所以亏损。Wmax=-78,x=195,最小亏损78万元
W=X*Y-40Y=-0.08X^2+31.2X-1120 100<=X<=200
=-0.1X^2+36X-1280 X>200
W>=1842+78=1920 X>=200
X=200,Ymax=12
单价范围200到300元。销量最大为12万件,此时,单价为200元