log1/2 (3-x)≥log2 (x+3)-1
-log2 (3-x)≥log2 (x+3)-log2 2
log2 (3-x)+log2 (x+3)-log2 2≤0
log2 [(3-x)(x+3)/2]≤log2 1
因为2>1,所以log2 x为增函数
0<(3-x)(x+3)/2≤1
0<9-x²≤2
7≤x²<9
√7≤x<3或-3<x≤-√7
log1/2 (3-x)≥log2 (x+3)-1
-log2 (3-x)≥log2 (x+3)-log2 2
log2 (3-x)+log2 (x+3)-log2 2≤0
log2 [(3-x)(x+3)/2]≤log2 1
因为2>1,所以log2 x为增函数
0<(3-x)(x+3)/2≤1
0<9-x²≤2
7≤x²<9
√7≤x<3或-3<x≤-√7