设函数f(x)=sec x在x=0处的2次泰勒多项式为1+ax+bx²，则()．

A 极限不存在 B 极限存在，但不连续 C 连续，但不可导 D 可导

A <img width="56" height="37" src="https://www.beizhujiaoyu.com/uploads/202208/20211118125209_1803.jpg" /> B <img width="53" height="37" src="https://www.beizhujiaoyu.com/uploads/202208/20211118125211_8053.jpg" /> C <img width="56" height="36" src="https://www.beizhujiaoyu.com/uploads/202208/20211118125215_8054.jpg" /> D <img width="53" height="36" src="https://www.beizhujiaoyu.com/uploads/202208/20211118125216_5085.jpg" />

A 对x可偏导，对y不可偏导 B 对x不可偏导，对y可偏导 C 对x可偏导，对y也可偏导 D 对x不可偏导，对y也不可偏导

A <img width="159" height="77" src="https://www.beizhujiaoyu.com/uploads/202208/20210924231804_2264.jpg" /> B <img width="138" height="77" src="https://www.beizhujiaoyu.com/uploads/202208/20210924231805_9607.jpg" /> C <img width="107" height="77" src="https://www.beizhujiaoyu.com/uploads/202208/20210924231806_3826.jpg" /> D <img width="149" height="79" src="https://www.beizhujiaoyu.com/uploads/202208/20210924231808_2264.jpg" />

A 充分必要条件   B 充分而非必要条件 C 必要而非充分条件   D 既非必要也非充分条件

A (-2，2)． B 2． C (2，+∞)． D (-∞，-2)．

A P(B|<img width="24" height="42" src="https://www.beizhujiaoyu.com/uploads/202208/20211020135125_1800.gif" />)+P(A)P(B|<img width="24" height="42" src="https://www.beizhujiaoyu.com/uploads/202208/20211020135125_1800.gif" />)=P(B) B P(B|<img width="24" height="42" src="https://www.beizhujiaoyu.com/uploads/202208/20211020135125_1800.gif" />)-P(A)P(B|<img width="24" height="42" src="https://www.beizhujiaoyu.com/uploads/202208/20211020135125_1800.gif" />)=P(B) C P(B|<img width="24" height="42" src="https://www.beizhujiaoyu.com/uploads/202208/20211020135125_1800.gif" />)+P(A)P(B|<img width="24" height="42" src="https://www.beizhujiaoyu.com/uploads/202208/20211020135125_1800.gif" />)=P(<img width="24" height="42" src="https://www.beizhujiaoyu.com/uploads/202208/20211020135122_8988.gif" />) D P(B|<img width="24" height="42" src="https://www.beizhujiaoyu.com/uploads/202208/20211020135125_1800.gif" />)-P(A)P(B|<img width="24" height="42" src="https://www.beizhujiaoyu.com/uploads/202208/20211020135125_1800.gif" />)=P(<img width="24" height="42" src="https://www.beizhujiaoyu.com/uploads/202208/20211020135122_8988.gif" />)

A <img width="184" height="22" src="https://www.beizhujiaoyu.com/uploads/202208/20211118124010_1205.jpg" /> B <img width="174" height="22" src="https://www.beizhujiaoyu.com/uploads/202208/20211118124010_7582.jpg" /> C <img width="538" height="38" src="https://www.beizhujiaoyu.com/uploads/202208/20211118124012_3050.jpg" /> D <img width="625" height="22" src="https://www.beizhujiaoyu.com/uploads/202208/20211118124012_9144.jpg" />

A <img width="195" height="40" src="https://www.beizhujiaoyu.com/uploads/202208/20211118124016_9769.jpg" /> B <img width="195" height="40" src="https://www.beizhujiaoyu.com/uploads/202208/20211118124017_1800.jpg" /> C <img width="196" height="41" src="https://www.beizhujiaoyu.com/uploads/202208/20211118124019_1488.jpg" /> D <img width="195" height="40" src="https://www.beizhujiaoyu.com/uploads/202208/20211118124019_3519.jpg" />