摘要： 解:(1)设药物燃烧阶段函数解析式为.由题意得: ························································································································ 2分 ．此阶段函数解析式为······································································· 3分 (2)设药物燃烧结束后的函数解析式为.由题意得: ·························································································································· 5分 ．此阶段函数解析式为······································································ 6分 (3)当时.得···················································································· 7分 ························································································································· 8分 ·························································································································· 9分 从消毒开始经过50分钟后学生才可回教室．···························································· 10分

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