幂级数<img src='https://img2.soutiyun.com/latex/latex.action' />的收敛域为( )．

设a为常数，则级数<img src='https://img2.soutiyun.com/latex/latex.action' />( )．

已知两个线性变换<img src='https://img2.soutiyun.com/ask/2020-07-24/964447450539867.png' />，求从<img src='https://img2.soutiyun.com/ask/2020-07-24/964447482729708.png' />到<img src='https://img2.soutiyun.com/ask/2020-07-24/964447490132131.png' />的线性变换。

级数<img src='https://img2.soutiyun.com/latex/latex.action' />与∑<img src='https://img2.soutiyun.com/latex/latex.action' />满足u_n≤v_n(n=1，2，…)，则( )．

若<img src='https://img2.soutiyun.com/latex/latex.action' />，<img src='https://img2.soutiyun.com/latex/latex.action' />，则下列式子成立的是( )

设a为常数，则级数<img src='https://img2.soutiyun.com/ask/uploadfile/6681001-6684000/7528d38b5c08d705855c25ce86a7ee6d.png' />( )

若级数<img src='https://img2.soutiyun.com/latex/latex.action' />与<img src='https://img2.soutiyun.com/latex/latex.action' />分别收敛于S₁与S₂，则( )式未必成立．

设f(x)以2π为周期，<img src='https://img2.soutiyun.com/ask/uploadfile/6681001-6684000/04820dd60870b1dd31e972d33b85c0e5.png' />，s(x)为f(x)的傅里叶级数、和函数，则( )

已知z=lnu，<img src='https://img2.soutiyun.com/latex/latex.action' />，则<img src='https://img2.soutiyun.com/latex/latex.action' />( )

级数<img src='https://img2.soutiyun.com/latex/latex.action' />收敛，则必有( )．

设<img src='https://img2.soutiyun.com/latex/latex.action' />则<img src='https://img2.soutiyun.com/latex/latex.action' />=( )．

幂级数<img src='https://img2.soutiyun.com/latex/latex.action' />的收敛半径R=( )．

当( )时，无穷级数<img src='https://img2.soutiyun.com/latex/latex.action' />(u＞0)绝对收敛．

男性，40岁，发现左侧颈部小包块，CT、MRI检查如图所示，请选择最可能的诊断（）<img src='https://img2.soutiyun.com/shangxueba/ask/18300001-18303000/18301269/2016072818164956119.jpg' /><img src='https://img2.soutiyun.com/shangxueba/ask/18300001-18303000/18301269/2016072818165646074.jpg' /><img src='https://img2.soutiyun.com/shangxueba/ask/18300001-18303000/18301269/2016072818170225050.jpg' /><img src='https://img2.soutiyun.com/shangxueba/ask/18300001-18303000/18301269/20160728181708767.jpg' />

利用幂级数展开，计算<img src='https://img2.soutiyun.com/shangxueba/ask/51432001-51435000/51432829/980695520313543.png' />。

幂级数<img src='https://img2.soutiyun.com/shangxueba/ask/17670001-17673000/17671982/2015102915280779420.jpg' />

病历摘要：脑膜瘤患者女，55岁，视力下降数月。查体：视力下降，余神经体征阴性。<img src='https://img2.soutiyun.com/shangxueba/ask/21054001-21057000/21056152/2016080411361155670.jpg' /><img src='https://img2.soutiyun.com/shangxueba/ask/21054001-21057000/21056152/2016080411363213140.jpg' /><img src='https://img2.soutiyun.com/shangxueba/ask/21054001-21057000/21056152/2016080411363770796.jpg' /><img src='https://img2.soutiyun.com/shangxueba/ask/21054001-21057000/21056152/2016080411364194722.jpg' /><img src='https://img2.soutiyun.com/shangxueba/ask/21054001-21057000/21056152/2016080411364682394.jpg' /><img src='https://img2.soutiyun.com/shangxueba/ask/21054001-21057000/21056152/2016080411365145350.jpg' />

将函数f(x)＝x²在<img src='https://img2.soutiyun.com/shangxueba/ask/18735001-18738000/18737342/2016071617062459326.jpg' />上展开成余弦级数，其形式为<img src='https://img2.soutiyun.com/shangxueba/ask/18735001-18738000/18737342/2016071617063532608.jpg' /><img src='https://img2.soutiyun.com/shangxueba/ask/18735001-18738000/18737342/2016071617065141640.jpg' />（）<img src='https://img2.soutiyun.com/shangxueba/ask/18735001-18738000/18737342/2016071617071375522.jpg' />

某一水泵的流量为<img src='https://img2.soutiyun.com/shangxueba/ask/18726001-18729000/18727196/20150618111622761.jpg' />，漏损流量为<img src='https://img2.soutiyun.com/shangxueba/ask/18726001-18729000/18727196/2015061811163167874.jpg' />，叶轮内的流量为<img src='https://img2.soutiyun.com/shangxueba/ask/18726001-18729000/18727196/2015061811163945969.jpg' />，则其容积效率<img src='https://img2.soutiyun.com/shangxueba/ask/18726001-18729000/18727196/2015061811164812800.jpg' />为（）。

利用上颌双侧<img src='https://img2.soutiyun.com/shangxueba/ask/17559001-17562000/17561302/2015093009262249313.jpg' />垫矫正反<img src='https://img2.soutiyun.com/shangxueba/ask/17559001-17562000/17561302/2015093009262249313.jpg' />，反<img src='https://img2.soutiyun.com/shangxueba/ask/17559001-17562000/17561302/2015093009262249313.jpg' />解除后<img src='https://img2.soutiyun.com/shangxueba/ask/17559001-17562000/17561302/2015093009262249313.jpg' />垫每次应磨去多少（）

一台4极中型异步电动机，P_N=200kW，U_N=380V,定子0联接，定子额定电流I_N=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:

设<img src='https://img2.soutiyun.com/shangxueba/ask/51291001-51294000/51293683/975264374908477.png' />是n维实向量,且<img src='https://img2.soutiyun.com/shangxueba/ask/51291001-51294000/51293683/975264387229182.png' />战性无关,<img src='https://img2.soutiyun.com/shangxueba/ask/51291001-51294000/51293683/975264401121976.png' /><img src='https://img2.soutiyun.com/shangxueba/ask/51291001-51294000/51293683/975264415373792.png' />是线性方程组

（2013）正项级数<img src='https://img2.soutiyun.com/shangxueba/ask/19032001-19035000/19033100/2015110315490562976.png' />的部分和数列<img src='https://img2.soutiyun.com/shangxueba/ask/19032001-19035000/19033100/2015110315495812105.png' />有上界是该级数收敛的：（）

若<img src='https://img2.soutiyun.com/latex/latex.action' />，<img src='https://img2.soutiyun.com/latex/latex.action' />试证明时域卷积定理<img src='https://img2.soutiyun.com/latex/latex.action' />和频域卷积定理<img src='https://img2.soutiyun.com/latex/latex.action' />

男，4个月，相貌怪异，结合图像，最可能的诊断（）<img src='https://img2.soutiyun.com/shangxueba/ask/17796001-17799000/17798971/201511231032013640.jpg' /><img src='https://img2.soutiyun.com/shangxueba/ask/17796001-17799000/17798971/2015112310320224881.jpg' /><img src='https://img2.soutiyun.com/shangxueba/ask/17796001-17799000/17798971/201511231032042853.jpg' /><img src='https://img2.soutiyun.com/shangxueba/ask/17796001-17799000/17798971/2015112310320644602.jpg' />