算术平方根有意义,x²-1≥0x≥1或x≤-1真数有意义,x+√(x²-1)>01/[x-√(x²-1)]>0x-√(x²-1)>0x>√(x²-1)≥0x≥1x+√(x²-1)≥1log(1/2)(x+√(x²-1))≤0要方程有解,a≤0...