题目

    济南与北京两地相距480千米，乘坐高铁列车比乘坐普通快车能提前4小时到达．已知高铁列车的平均行驶速度是普通快车的3倍，求高铁列车的平均行驶速度. 答案：解：设普通快车的速度为xkm/h，由题意得：·················································· 1分 ·································································································· 3分 =4············································································································ 4分 x=80················································································································ 5分 经检验x=80是原分式方程的解········································································ 6分 3x=3×80=240 ·································································································· 7分 答：高铁列车的平均行驶速度是240km/h．····················································· 8分

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