己知命题“∃x∈R,使2x2+(a-1)x+1/2≤0”是假命题,则实数a的取值范围是 _ .
问题描述:
己知命题“∃x∈R,使2x2+(a-1)x+
≤0”是假命题,则实数a的取值范围是 ___ .1 2
答
∵命题“∃x∈R,使2x2+(a-1)x+
≤0”是假命题,1 2
∴命题“∀x∈R,使2x2+(a-1)x+
>0”是真命题,1 2
即判别式△=(a-1)2-4×2×
<0,1 2
即△=(a-1)2<4,
则-2<a-1<2,即1<a<3,
故答案为:(1,3).