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1、【答案】解:(Ⅰ)填表:t≤150150＜t＜350t=350t＞350式计费/元580.25t+20.51080.25t+20.5式二计费/元8888880.19t+21.5(Ⅱ)∵t＞350(0.25t+20.5)-(0.19t+21.5)=0.06t-1＞0∴两种计费式费用相等t值150＜t＜350取.∴列程0.25t+20.5=88解t=270∴主叫间270两种计费式费用相等(Ⅲ)式二理由:式收费-式二收费y=0.25t+20.5-0.19t-21.5=0.06t-1∵330＜t＜360y＞0∴式二更划算.答:330＜t＜360式二计费式省钱【考点】列代数式元程应用【析】(I)根据两种式收费标准进行计算即:①150＜t＜350式收费:58+0.25(x-150)=0.25t+20.5;②t＞350式收费:58+0.25(x-150)=0.25t+20.5;③式二t＞350收费:88+0.19(x-350)=0.19t+21.5.(II)先判断两种式相等t致范围建立程即答案(III)计算两种式区间收费情况比较即答案。

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