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> 济宁市“五城同创”活动中,一项绿化工程由甲、乙两工程队承担.已知甲工程队单独完成这项工作需120天,甲工程队单独工作30天后,乙工程队参与合做,两队又共同工作了36天完成-七年级数学
济宁市“五城同创”活动中,一项绿化工程由甲、乙两工程队承担.已知甲工程队单独完成这项工作需120天,甲工程队单独工作30天后,乙工程队参与合做,两队又共同工作了36天完成-七年级数学
题目简介
济宁市“五城同创”活动中,一项绿化工程由甲、乙两工程队承担.已知甲工程队单独完成这项工作需120天,甲工程队单独工作30天后,乙工程队参与合做,两队又共同工作了36天完成-七年级数学
题目详情
济宁市“五城同创”活动中,一项绿化工程由甲、乙两工程队承担.已知甲工程队单独完成这项工作需120天,甲工程队单独工作30天后,乙工程队参与合做,两队又共同工作了36天完成.
(1)求乙工程队单独完成这项工作需要多少天?
(2)因工期的需要,将此项工程分成两部分,甲做其中一部分用了x天完成,乙做另一部分用了y天完成,其中x、y均为正整数,且x<46,y<52,求甲、乙两队各做了多少天?
题型:解答题
难度:中档
来源:不详
答案
(1)乙工程队单独做需要80天完成;(2)甲队做了45天,乙队做了50天.
试题分析:(1)根据“甲工程队单独完成这项工作需120天,甲工程队单独工作30天后,乙工程队参与合做,两队又共同工作了36天完成”,设乙工程队单独完成这项工作需要x天,列出方程求解即可;
(2)因为甲队做其中一部分用了x天,乙队做另一部分用了y天,可得到方程
,再根据x<46,y<52,得到方程组
,其中x、y均为正整数,解此方程组即可得到答案.
试题解析:(1)设乙工程队单独完成这项工作需要x天,由题意得
,解之得x=80.···················································3分
经检验x=80是原方程的解.
答:乙工程队单独做需要80天完成.·······················································4分
(2)因为甲队做其中一部分用了x天,乙队做另一部分用了y天,
所以
,即
,又x<46,y<52,·····························5分
所以
,解之得42<x<46,
因为x、y均为正整数,所以x=45,y=50.·················································7分
答:甲队做了45天,乙队做了50天.···························································8分
上一篇 :
方程-=0的解为()A.x=2B.x=-2C.x=3D.x=-3
下一篇 :
解方程:=1﹣.-七年级数学
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题目简介
济宁市“五城同创”活动中,一项绿化工程由甲、乙两工程队承担.已知甲工程队单独完成这项工作需120天,甲工程队单独工作30天后,乙工程队参与合做,两队又共同工作了36天完成-七年级数学
题目详情
(1)求乙工程队单独完成这项工作需要多少天?
(2)因工期的需要,将此项工程分成两部分,甲做其中一部分用了x天完成,乙做另一部分用了y天完成,其中x、y均为正整数,且x<46,y<52,求甲、乙两队各做了多少天?
答案
试题分析:(1)根据“甲工程队单独完成这项工作需120天,甲工程队单独工作30天后,乙工程队参与合做,两队又共同工作了36天完成”,设乙工程队单独完成这项工作需要x天,列出方程求解即可;
(2)因为甲队做其中一部分用了x天,乙队做另一部分用了y天,可得到方程
试题解析:(1)设乙工程队单独完成这项工作需要x天,由题意得
经检验x=80是原方程的解.
答:乙工程队单独做需要80天完成.·······················································4分
(2)因为甲队做其中一部分用了x天,乙队做另一部分用了y天,
所以
所以
因为x、y均为正整数,所以x=45,y=50.·················································7分
答:甲队做了45天,乙队做了50天.···························································8分