y=xsinx+2cosx[x∈()]的拐点坐标是()．

A 1 B 2 C 3 D 4

A <img src="https://www.beizhujiaoyu.com/uploads/202208/161966268719131.png" width="81" height="33" />  B <img src="https://www.beizhujiaoyu.com/uploads/202208/161966269240111.png" width="90" height="33" />  C <img src="https://www.beizhujiaoyu.com/uploads/202208/161966269631131.png" width="105" height="35" />  D <img src="https://www.beizhujiaoyu.com/uploads/202208/161966270033931.png" width="90" height="35" /> 

A 1，0，1 B 1，0，2 C 2，1，3 D 2，1，4

A I₃＜I₂＜I₁ B I₂＜I₁＜I₃ C I₁＜I₂＜I₃ D I₂＜I₃＜I₁

A 充分非必要条件 B 充分必要条件 C 必要非充分条件 D 既非充分又非必要条件

A 0 B 1 C 2 D 3

A <img src="https://www.beizhujiaoyu.com/uploads/202208/161966272564971.png" width="102" height="32" /> B <img src="https://www.beizhujiaoyu.com/uploads/202208/161966273010491.png" width="97" height="32" /> C <img src="https://www.beizhujiaoyu.com/uploads/202208/161966273685051.png" width="90" height="32" /> D <img src="https://www.beizhujiaoyu.com/uploads/202208/161966274114961.png" width="100" height="32" />