设全集U＝R,集合A＝{x|-1≤x0},满足B∪C＝C,求实数a的取值范围
B={x|2x-4≥x-2}={x|x≥2},
C={x|2x+a>0}={x|x>-0.5a},
B∪C＝C
-0.5a≥2
a≤-4
实数a的取值范围是a≤-4