Question

下列函数满足“对∀x₁，x₂∈(0，＋∞)且x₁≠x₂时恒有<0”的是                                                                                          (　　)

A．f(x)＝                        B．f(x)＝(x－1)²

C．f(x)＝e^x                         D．f(x)＝ln(x＋1)

Answer 1

A

解析　条件即f(x)在(0，＋∞)为减函数，只有符合条件．