设函数f(x)=ax-bln x(a>o)有2个零点，则b/a的取值范围是()．

A 低阶无穷小 B 等价无穷小 C 高阶无穷小 D 同阶但非等价无穷小

A 连续且取得极大值 B 连续且取得极小值 C 可导且导数为零 D 可导且导数不为零

A 125πcm³／s，40πcm²／s B 125πcm³／s，-40πcm²／s C -100πcm³／s，40πcm²／s D -100πcm³／s，-40πcm²／s

A a=1，b=-<img src="https://www.beizhujiaoyu.com/uploads/202208/161966141920991.png" width="15" height="39" title="" align="" alt="" /> B a=1，b=<img src="https://www.beizhujiaoyu.com/uploads/202208/161966142592361.png" width="15" height="39" title="" align="" alt="" /> C a=0，b=-<img src="https://www.beizhujiaoyu.com/uploads/202208/161966143059371.png" width="15" height="39" title="" align="" alt="" /> D a=0，b=<img src="https://www.beizhujiaoyu.com/uploads/202208/161966143639851.png" width="15" height="39" title="" align="" alt="" />

A dx+dy B dx-dy C dy D -dy

A <img src="https://www.beizhujiaoyu.com/uploads/202208/161966145162531.png" width="140" height="39" />  B <img src="https://www.beizhujiaoyu.com/uploads/202208/161966145726021.png" width="140" height="39" />  C <img src="https://www.beizhujiaoyu.com/uploads/202208/161966146298421.png" width="132" height="42" />  D <img src="https://www.beizhujiaoyu.com/uploads/202208/161966146739831.png" width="111" height="42" /> 

A 2，0 B 1，1 C 2，1 D 1，2

A Ax=0的解均为Bx=0的解 B A^Tx=0的解均为B^Tx=0的解 C Bx=0的解均为Ax=0的解 D B^TX=0的解均为A^Tx=0的解

A <img src="https://www.beizhujiaoyu.com/uploads/202208/16196614759371.png" width="167" height="74" />  B <img src="https://www.beizhujiaoyu.com/uploads/202208/161966148173021.png" width="198" height="74" />  C <img src="https://www.beizhujiaoyu.com/uploads/202208/16196614854121.png" width="198" height="75" />  D <img src="https://www.beizhujiaoyu.com/uploads/202208/161966148911951.png" width="194" height="75" />