下列函数在x=0处不可导的是（）．

A z=0与x+y-z=1 B z=0与2x+2y-z=2 C y=x与x+y-z=1 D y=x与2x+2y-z=2

A sin1+cos1 B 2sin1+cos1 C 2sin1+2cos1 D 2sin1+3cos1

A M>N>K B M>K>N C K>M>N D K>N>M

A <img src="https://www.beizhujiaoyu.com/uploads/202208/162087909799571.png" alt="" width="50" height="47" title="" align="" /> B <img src="https://www.beizhujiaoyu.com/uploads/202208/162087912154581.png" alt="" width="50" height="47" title="" align="" /> C <img src="https://www.beizhujiaoyu.com/uploads/202208/162087913841591.png" alt="" width="50" height="45" title="" align="" /> D <img src="https://www.beizhujiaoyu.com/uploads/202208/162087915688691.png" alt="" width="50" height="45" title="" align="" />

A r(A，AB)=r(A) B r(A，BA)=r(A) C r(A，B)=max{r(A)，r(B)} D r(A，B)=r(A^T，B^T)

A 0．2 B 0．3 C 0．4 D 0．5

A 若显著性水平α=0．05下拒绝H₀，则α=0．01下必拒绝H₀ B 若显著性水平α=0．05下接受H₀，则α=0．01下必拒绝H₀ C 若显著性水平α=0．05下拒绝H₀，则α=0．01下接受H₀ D 若显著性水平α=0．05下接受H₀，则α=0．01下也接受H₀