甲、乙两人参加一次英语口语考试,已知在备选的10道试题中,甲能答对其中6题,乙能答对其中的8题,规定每次考试都从备选题中随机抽出3题进行测试,至少答对2题才算合格.
(1)求甲答对试题数不多于2道的概率;
(2)求甲、乙两人至少有一人考试合格的概率.
考点分析:
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设函数
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(1)求f(x)的最小正周期;
(2)在△ABC中,a,b,c分别是角A,B,C的对边,
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,求b,c的长.
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给出下列命题
①若命题P和命题Q中只有一个是真命题,则¬P或Q是假命题;
②
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或
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是
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成立的必要不充分条件;
③若定义在R上的函数y=f(x)满足f(x+1)=1-f(x),则f(x)是周期函数;
④若
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,则r的取值范围是
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.
其中所有正确命题的序号是
.
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已知|
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|=1,|
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|=
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,
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=0,点C在∠AOB内,且∠AOC=30°,设
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=m
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+n
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(m、n∈R),则
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等于
.
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设x,y为正数,则
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的最小值是
.
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已知函数
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在x=1处连续,则实数a的值为
.
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