初三一元二次方程应用题一题:世博会期间上海某宾馆有50个房间可供游客...答:1.①180≤x≤230时 y=50-(x-180)/10=68-0.1x x∈{180,190,200,210,220,230} ②x>230时 y=50-50/10-(x-230)/10*2=45-(x-230)/5=91-0.2x 91-0.2x≥50*(1-1/3)解得:x≤865/3 x∈{240,250,260,270,280} 2.①x∈{180,190,200,210,220,230} 利润:(68-0.1...