的第二类间断点的个数为

A b sin a B b cos a C b sin f(a) D b cos f(a)

A <img width="240" height="33" src="https://www.beizhujiaoyu.com/uploads/202208/20210429182825_2418.jpg" title="" align="" alt="" /> B <img width="240" height="32" src="https://www.beizhujiaoyu.com/uploads/202208/20210429182826_8355.jpg" title="" align="" alt="" /> C <img width="240" height="32" src="https://www.beizhujiaoyu.com/uploads/202208/20210429182827_4293.jpg" title="" align="" alt="" /> D <img width="240" height="33" src="https://www.beizhujiaoyu.com/uploads/202208/20210429182829_1012.jpg" title="" align="" alt="" />

A (-2，6) B (-3，1) C (-5，3) D (-17，15)

A x=k₁α₁+k₂α₂+k₃α₃，其中k₁，k₂，k₃为任意常数 B x=k₁α₁+k₂α₂+k₃α₄，其中k₁，k₂，k₃为任意常数 C x=k₁α₁+k₂α₃+k₃α₄，其中k₁，k₂，k₃为任意常数 D x=k₁α₂+k₂α₃+k₃α₄，其中k₁，k₂，k₃为任意常数

A (α₁+α₃，α₂，-α₃) B (α₁+α₂，α₂，-α₃) C (α₁+α₃，-α₃，α₂) D (α₁+α₂，-α₃，α₂)

A <img width="20" height="52" src="https://www.beizhujiaoyu.com/uploads/202208/20210429182835_1168.gif" title="" align="" alt="" /> B <img width="20" height="52" src="https://www.beizhujiaoyu.com/uploads/202208/20210429182837_1481.gif" title="" align="" alt="" /> C <img width="20" height="52" src="https://www.beizhujiaoyu.com/uploads/202208/20210429182837_3512.gif" title="" align="" alt="" /> D <img width="24" height="47" src="https://www.beizhujiaoyu.com/uploads/202208/20210429182839_4293.gif" title="" align="" alt="" />

A <img width="80" height="40" src="https://www.beizhujiaoyu.com/uploads/202208/20210429182841_6815.jpg" title="" align="" alt="" /> B <img width="80" height="39" src="https://www.beizhujiaoyu.com/uploads/202208/20210429182841_9606.jpg" title="" align="" alt="" /> C <img width="80" height="39" src="https://www.beizhujiaoyu.com/uploads/202208/20210429182843_9293.jpg" title="" align="" alt="" /> D <img width="80" height="39" src="https://www.beizhujiaoyu.com/uploads/202208/20210429182844_2106.jpg" title="" align="" alt="" />