在一项商业活动中,某人获利300元的概率是0.6,亏损100元的概率是0.4,那么他经营的期望值是________.

在一项商业活动中,某人获利300元的概率是0.6,亏损100元的概率是0.4,那么他经营的期望值是________.

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过圆x2+y2=25上一点M(-4,3)作该圆的切线,则此切线方程为__________.

过圆x2+y2=25上一点M(-4,3)作该圆的切线,则此切线方程为__________.

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Some people claim that television is good for children becau

Some people claim that television is good for children because it gets children

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