设全集为R,集合A={y|y=sin2x,π/6大于等于x小于等于3π/4},集合B={a∈设全集为R，集合A={y|y=sin2x，π/6大于等于x小于等于3π/4}，集合B={a∈R|关于x的方程x^2+ax+1=0有两个不相等的实数根}(1)求集合A,B(2)(

Question

设全集为R,集合A={y|y=sin2x,π/6大于等于x小于等于3π/4},集合B={a∈
设全集为R，集合A={y|y=sin2x，π/6大于等于x小于等于3π/4}，集合B={a∈
R|关于x的方程x^2+ax+1=0有两个不相等的实数根} (1)求集合A,B(2) (CRA)交(CRB)

Answer 1

π/6<=x<=3π/4
π/3<=2x<=3π/2
π/2<=2x<=3π/2时,sin2x是减函数
所以sin3π/2<=sin2x<=sinπ/2
-1<=sin2x<=1
所以A={y|-1<=y<=1}
有两个不相等的实数根
a^2-4>0
a>2,a所以B={a|a>2,aCRA={y|y1
CRB={a|-2<=a<=2}
交集即公共部分
所以 (CRA)交(CRB)={b|-2<=b

作业帮用户 2016-12-05 举报