k=0
则-1>0
满足解集为空集
k≠0
解集为空集则kx²+2kx-1<=0恒成立
所以开口向下,k<0
且△<=0
4k²+4k<=0
4k(k+1)<=0
-1<=k<0
综上
-1<=k<=0 k=0
则-1>0
满足解集为空集
k≠0
解集为空集则kx²+2kx-1<=0恒成立
所以开口向下,k<0
且△<=0
4k²+4k<=0
4k(k+1)<=0
-1<=k<0
综上
-1<=k<=0