齐次线性方程组<img src='https://img2.soutiyun.com/shangxueba/ask/1497001-1500000/1497017/ct_kgctem_kgctechoose_0050(106)1.jpg' />的系数矩阵为A，若有3阶非零矩阵B使AB=0，则()。
质量改进小组决定改进标准差，经过努力，把该过程的标准差由1．1减小到0．7，<img src='https://img2.soutiyun.com/ask/uploadfile/5853001-5856000/5661ca6502387419ea87f4836437605a.png' />
应用在空调机上的整流电路，输出电压为如0 V， 测得的电流为0. 5 A， 则负载的等效电阻为（）<img src='' jquery111005450221144239208=' /><img src='https://img2.soutiyun.com/ask/uploadfile/5265001-5268000/8525602aed298ae87ad044b1dbcb7d19.gif' />
孔隙率P′计算公式<img src='https://img2.soutiyun.com/ask/uploadfile/10173001-10176000/c8b1d26d4107a58c193b1d1cb9356dfe.png' />式中ρ0′为()
三相四线制对称电源<img src='https://img2.soutiyun.com/ask/6489001-6492000/b6353df5b02f35836ce61033b0de5fcd.jpg' />，接入一个三角形连接的对称三相负载后，<img src='https://img2.soutiyun.com/ask/6489001-6492000/2f7cb60cbe77c048a52a64e8c331e4f0.jpg' />，该负载消耗的功率P=( )。
对于一个投资项目，其投入物和产出物可分为几类？<img src='https://img2.soutiyun.com/ask/uploadfile/12555001-12558000/50c7916020a66f82ddaac17c0178b8a0.gif' />
已知平面图形中基点A的速度为VA，平面图形相对于A点的角速度ωA≠0。问下述说法错误的是（)。<img src='https://img2.soutiyun.com/shangxueba/ask/68949001-68952000/68949591/990464399580646.png' />
Two sides of a right triangle are 5 and Which of the following could be the length of the third side？<img src='https://img2.soutiyun.com/ask/uploadfile/2169001-2172000/4fc3fa773ba3ff1b4a790c7f86a536e7.jpg' />
设A、B为任意两事件，且<img src='https://img2.soutiyun.com/ask/2020-03-06/952348543191874.png' />，P(B)＞0，则下列选项必然成立的是( )
如图，当V<sub>A</sub>=V<sub>B</sub>=0时，V<sub>Z</sub>=（）V。<img src='https://img2.soutiyun.com/shangxueba/ask/18495001-18498000/18497830/2015062514434232068.jpg' />
设a≠0,|r|＜1,求<img src='https://img2.soutiyun.com/ask/2020-10-26/972583970755153.png' />
Refertotheexhibit.Assumethattheroutingprotocolreferencedineachchoicebelowisconfiguredwithitsdefaultsettingsandthegivenroutingprotocolisrunningonalltherouters.Whichtwoconditionalstatementsaccuratelystatethepaththatwillbechosenbetweennetworks10.1.0.0and10.3.2.0fortheroutingprotocolmentioned？（）<img src='https://img2.soutiyun.com/ask/uploadfile/2019-03-27/8c5149bf00080d2336a04f29e086f031.jpg' />
已知反应2A（g）+3B（s）<img src='https://img2.soutiyun.com/shangxueba/ask/19071001-19074000/19071965/2015102710104941329.jpg' />2C（g）+D（g）△H<0为使A的转化率达到最大，应采取的措施是（）
A,B为n阶可逆矩阵，0为n阶零矩阵，则<img src='https://img2.soutiyun.com/ask/2020-08-13/966181360564986.png' />
空心圆轴的内径为d，外径为D，α=<img src='https://img2.soutiyun.com/ask/2019-06-19/929792319178327.png' />=0.5。当横截面上扭矩为T时，最大切应力为τ。若截面上A点距外周边的距离为0.1D，则A点的切应力是______。<img src='https://img2.soutiyun.com/ask/2019-06-19/92979232682234.png' />
以下关于积矩相关系数（用r表示）的说法正确的有（）。A．<img src='https://img2.soutiyun.com/ask/uploadfile/5448001-5451000/d33b4471146495523c117a0280286149.jpg' />B．当|r|=0时，表示两指标变量完全线性相关C．0＜|r|≤0．3为微弱相关D．0．8＜|r|＜1为低度相关
在题设及题1的条件下，测得样本均值<img src='https://img2.soutiyun.com/ask/uploadfile/3321001-3324000/1c1e65640a66a8dca3523bf4bf91556a.jpg' />，假定显著水平α=0.05，则袋装饼干的平均重量是()。<img src='https://img2.soutiyun.com/ask/uploadfile/3321001-3324000/2f4de9cca1d5c614f801fd43260831de.jpg' />
A jar contains only red, yellow, and orange marbles. If there are 3 red, 5 yellow, and 4 orange marbles, and 3 marbles are chosen from the jar at random without replacing any of them, what is the probability that 2 yellow, 1 red, and no orange marbles will be chosen？<img src='https://img2.soutiyun.com/ask/uploadfile/2880001-2883000/63157f6fece0ba063c204840c3bccdec.jpg' /><img src='https://img2.soutiyun.com/ask/uploadfile/2880001-2883000/da2c83b4d3db68ec6001dbf42581e19e.jpg' />E．
一台4极中型异步电动机，P<sub>N</sub>=200kW，U<sub>N</sub>=380V,定子0联接，定子额定电流I<sub>N</sub>=385A,频率50Hz,定子铜耗<img src='https://img2.soutiyun.com/ask/2021-01-03/978560273352189.png' />=5.12kW.转子铜耗<img src='https://img2.soutiyun.com/ask/2021-01-03/978560286697952.png' />=2.85kW,铁耗<img src='https://img2.soutiyun.com/ask/2021-01-03/978560298531629.png' />=3.8kW，机械损耗<img src='https://img2.soutiyun.com/ask/2021-01-03/97856031340548.png' />=0.98kW，附加损耗<img src='https://img2.soutiyun.com/ask/2021-01-03/978560322980028.png' />=3kW，<img src='https://img2.soutiyun.com/ask/2021-01-03/978560339469971.png' />.正常运行时<img src='https://img2.soutiyun.com/ask/2021-01-03/978560353474772.png' />，起动时<img src='https://img2.soutiyun.com/ask/2021-01-03/978560375203015.png' />，由于磁路饱和与趋肤效应的影响，<img src='https://img2.soutiyun.com/ask/2021-01-03/978560441999835.png' /><img src='https://img2.soutiyun.com/ask/2021-01-03/97856039470213.png' />.试求:
已知反应2A（g）+3B（s）<img src='https://img2.soutiyun.com/shangxueba/ask/18597001-18600000/18598568/2016071715471264822.jpg' />2C（g）+D（g）△H<0为使A的转化率达到最大，应采取的措施是：（）
<img src='https://img2.soutiyun.com/shangxueba/ask/2022-04/26/271/20220426114349523.png' />=（），其中<img src='https://img2.soutiyun.com/shangxueba/ask/2022-04/26/423/20220426114358134.png' />为定向闭折线ABCA，这里的A,B,C依次为（1，0，0），（0，1，0）和（0，0，1）。
设L是从A（1，0）到B（-1，2）的线段，则曲线积分<img src='https://img2.soutiyun.com/shangxueba/ask/17670001-17673000/17672554/201510271143115588.jpg' />（x+y）ds等于：（）
设n阶矩阵A满足A<sup>m</sup>=0，m是正整数，试证E-A可逆，且<img src='https://img2.soutiyun.com/ask/2020-11-26/975228984878283.png' />
如图a所示，光滑直管AB，长l，在水平面内以匀角速w绕铅垂轴0：转动，另有一小球在管内作相对运动。初瞬时，小球在B端，相对速度为<img src='https://img2.soutiyun.com/ask/2021-02-18/9825157549438.png' />指向固定端A。问<img src='https://img2.soutiyun.com/ask/2021-02-18/982515713446426.png' />应为多少，小球恰能达到A端。
