矩阵A适合条件（ ）时，它的秩为.http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/b86f239936464d0ca8b1b6a23bb36044.png
举一反三
- 要使<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/c4b80714c3b14a559ae5bdcd09ef1fc6.png"/>是线性方程组AX=0的基础解系，则只要系数矩阵A=（ ）. A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/fb16cbefa5a746599e585bcf30dce878.png"/> B: ［2 1 1］ C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/df5d7a834bd44f44a519eaffffd47d39.png"/> D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/5adacc7663b444d69f148ab2e7a11cf1.png"/>
- 一定量的理想气体，在温度不变的条件下，当压强降低时，分子的平均碰撞频率<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/5499a59dc3754bfdbf231e19c5e2edb9.png" />和平均自由程<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/bba421d6506c4072b583fd4e63b5df81.png" />的变化情况是（ ）： A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/5499a59dc3754bfdbf231e19c5e2edb9.png" />和<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/bba421d6506c4072b583fd4e63b5df81.png" />都减小． B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/5499a59dc3754bfdbf231e19c5e2edb9.png" />减小而<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/bba421d6506c4072b583fd4e63b5df81.png" />增大． C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/5499a59dc3754bfdbf231e19c5e2edb9.png" />和<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/bba421d6506c4072b583fd4e63b5df81.png" />都增大． D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/5499a59dc3754bfdbf231e19c5e2edb9.png" />增大而<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/bba421d6506c4072b583fd4e63b5df81.png" />减小．
- 在电感元件的交流电路中，已知<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/a818ffec501541eaacdc3fd4b3458bfa.png" />，则（ ）。 A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/70961d125a8a493cbdbd3169e8655336.png" /> B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/65f4ae24f45041548b04d5bb8c113767.png" /> C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/20d9ff741d534721b621dfe04fb3b2bd.png" />
- 设某微观粒子的相对论动量是它非相对论动量的<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/f04bc52895444aa9bf3ce69591507d4b.png" />倍，则其运动速度的大小为：（ c 表示真空中的光速）（ ）。 A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/39876687533246689c09bf2af4be1fe2.png" /> B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/dd046c8367ec4635b34aaad5ceffe48b.png" /> C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/99f25f4748cf434c96c5fa7552098ff5.png" /> D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/85033bc491434663a83ffea2611f0c2b.png" />
- 如图所示的一细螺绕环，它由表面绝缘的导线在铁环上密绕而成，每厘米绕10匝．当导线中的电流I 为2．0 A时，测得铁环内的磁感应强度的大小 B 为1．0 T，则可求得铁环的相对磁导率<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/c31a3f1826e440f79e7fb4077c8b5656.png" />为（真空磁导率<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/6323a02b04c04433b348982bca792a04.png" />）（ ）<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/21646345be094027b95dfa1075514903.png" /> A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/d61b3d6b1b664ff7a7271955ea8cb90c.png" /> B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/8599397fd0ad4c8a8ce382fc6eda4fd4.png" /> C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/092b8a5debaa47f899b9745dba2a6492.png" /> D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/6647d96f362c41879bd44d76722c7092.png" />