作业帮某次数学竞赛共有20道选择题,答对一题记5分,答错一题扣2分,不答记0分.某同学共得48分,那么他最多答对了几题?英语:A man from the UK remembered the correct order of 1820 playing cards,after seeing them just once.(
来源：学生作业帮助网 编辑：作业帮 时间：2024/04/24 19:20:54
某次数学竞赛共有20道选择题,答对一题记5分,答错一题扣2分,不答记0分.某同学共得48分,那么他最多答对了几题?英语:A man from the UK remembered the correct order of 1820 playing cards,after seeing them just once.(
某次数学竞赛共有20道选择题,答对一题记5分,答错一题扣2分,不答记0分.某同学共得48分,那么他最多答对了几题?
英语:A man from the UK remembered the correct order of 1820 playing cards,after seeing them just once.(用从句转换)
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某次数学竞赛共有20道选择题,答对一题记5分,答错一题扣2分,不答记0分.某同学共得48分,那么他最多答对了几题?英语:A man from the UK remembered the correct order of 1820 playing cards,after seeing them just once.(
设做对X道,错Y道
5X-2Y=48 (1)
X+Y≤20 (2)
由(1)得,Y=(5X-48)/2 (3)
把(3)带入(2)得
7X≤88
X≤88/7≈12.5
所以,最多做对了12题.
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A man from the UK remembered the correct order of 1820 playing cards,after seeing them just once.(用从句转换)
A man from the UK remembered the correct order of 1820 playing cards after he saw them just once.