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+

1
2
≤0”是假命题,则实数a的取值范围是 ___ .

∵命题“∃x∈R,使2x2+(a-1)x+

1
2
≤0”是假命题,
∴命题“∀x∈R,使2x2+(a-1)x+
1
2
>0”是真命题,
即判别式△=(a-1)2-4×2×
1
2
<0,
即△=(a-1)2<4,
则-2<a-1<2,即1<a<3,
故答案为:(1,3).