若命题“∃x∈R,使x2+(a-1)x+1<0”是假命题,则实数a的取值范围为(  )
1个回答

解题思路:由命题“∃x∈R,使x2+(a-1)x+1<0”是假命题,知∀x∈R,使x2+(a-1)x+1≥0,由此能求出实数a的取值范围.

∵命题“∃x∈R,使x2+(a-1)x+1<0”是假命题,

∴∀x∈R,使x2+(a-1)x+1≥0,

∴△=(a-1)2-4≤0,

∴-1≤a≤3.

故选D.

点评:

本题考点: 命题的真假判断与应用.

考点点评: 本题考查命题的真假判断和应用,解题时要注意由命题“∃x∈R,使x2+(a-1)x+1<0”是假命题,知∀x∈R,使x2+(a-1)x+1≥0,由此进行等价转化,能求出结果.