题干

给出下列四个命题:

①回归直线 y^=bx^+a 恒过样本中心点 (x¯y¯)

②“x=6”是“x2﹣5x﹣6=0”的必要不充分条件;

③“∃x0∈R,使得x02+2x0+3<0”的否定是“对∀x∈R,均有x2+2x+3>0”;

④“命题p∨q”为真命题,则“命题¬p∧¬q”也是真命题.

其中真命题的个数是(   )

A:0

B:1

C:2

D:3

上一题 下一题 0.0难度 选择题 更新时间:2018-10-26 01:14:08

答案(点此获取答案解析)

B

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