设集合A={x|x²+(a+2)x+1=0,x∈R},B=(0,+∞),A∩B=∅,求实数a的范围.
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设集合A={x|x²+(a+2)x+1=0,x∈R},B=(0,+∞),A∩B=∅,求实数a的范围.
设集合A={x|x²+(a+2)x+1=0,x∈R},B=(0,+∞),A∩B=∅,求实数a的范围.
设集合A={x|x²+(a+2)x+1=0,x∈R},B=(0,+∞),A∩B=∅,求实数a的范围.
A={x|x²+(a+2)x+1=0,x∈R},B=(0,+∞),A∩B=∅,
1.A=空集,则(a+2)^2-4<0
得-4<a<0
2.A≠空集,x²+(a+2)x+1=0无正根,
所以-(a+2)/2<0,且(a+2)^2-4≥0
得a≥0
综上,a>-4