已知全集 U=R, 集合 A={x | log0.5 ( 3-x ) ≥ -2},B= {x | 5 /x+2 ≥ 1}, 求 ( CuA )∩B
已知全集 U=R, 集合 A={x | log0.5 ( 3-x ) ≥ -2},B= {x | 5 /x+2 ≥ 1}, 求 ( CuA )∩B
優(yōu)質(zhì)解答
A
log0.5(3-x)>=log0.5(0.5^(-2))
所以0<3-x<=4
-1<=x<3
B
5/(x+2)-1>=0
(3-x)/(x+2)>=0
(x-3)(x+2)<=0
-2所以原式={x|x<-1,x>=3}∩{x|-2={x|-2