若集合A={x|x2+(k-3)x+k+5=0,x∈R},A∩R+≠Φ,则实数k的取值范围为_.

问题描述:

若集合A={x|x2+(k-3)x+k+5=0,x∈R},A∩R+≠Φ,则实数k的取值范围为______.

由题意知:方程x2+(k-3)x+k+5=0必有正根,从x2+(k-3)x+k+5=0中得
-k=

x2−3x+5
x+1
= x+1+
9
x+1
−5≥1,∴k≤-1
故填 (-∞,-1].