设0设0A f(a)B f((a+b)\2)C f(根号下ab)D f(b)设0当x>0时f(x)单调递减,又因为0当x>0时f(x)单调递减,又因为0故答案选Da当x>0时f(x)单调递减,又因为0故答案选D
设0当x>0时f(x)单调递减,又因为0
当x>0时f(x)单调递减,又因为0故答案选D
a