设（1)证明A（t)为单位矢量;（2)验证A·（dA/dt)=0;（3)求出|dA/dt|以说明单位矢量的导矢一般不再是

设平面不定常流动的速度分布为u=xt，υ=1，若在t=1时刻流体质点A位于(2，2)，试求(1)质点A的迹线方程； (2)在t=1、2、3时刻通过点(2，2)的流线方程。

设R为A到B的关系，S为B到C的关系，T，W<img src='https://img2.soutiyun.com/ask/2020-12-18/977161788236191.jpg' />A，证明： <img src='https://img2.soutiyun.com/ask/2020-12-18/97716181181354.jpg' />

设<img src='https://img2.soutiyun.com/ask/2020-11-26/975256358453962.png' />证明:R(A)=1,且存在常数k≠0,使A²=kA.

设f(x)为[-a，a]上的连续函数，证明： (1)若f(x)是偶函数，则<img src='https://img2.soutiyun.com/ask/2020-10-12/971368555517115.png' />是[-a，a]上的奇函数; (2)若f(x)是奇函数，则<img src='https://img2.soutiyun.com/ask/2020-10-12/971368586317876.png' />是[-a，a]上的偶函数。

设2阶矩阵<img src='https://img2.soutiyun.com/ask/2021-03-05/983805201384575.png' />证明: (1)若|A|＜0.则A可相似于对角矩阵; (2)若b,c同号，则A可相似于对角矩阵.

设a₁=(5,-8,-1,2)^T,a₂=(2,-1,4,-3)^T,a₃=(-3,2,-5,4)^T,从方程a₁+2a₂+3a_{3<img src='https://img2.soutiyun.com/ask/2020-11-26/97526278028527.png' />}

设A为n阶矩阵,<img src='https://img2.soutiyun.com/ask/2021-03-05/983793334730841.png' />证明:当k₁≠0,k₂≠0时,k₁ξ₁=k₂ξ₂不是A的特征向量.

<img src='https://img2.soutiyun.com/ask/2020-08-12/966083582354457.png' />

设a₁,a₂,…,a_n为互不相同的效，F(x)=(x-a₁)(x-a₂)…(x-a_n)。证明:任何多项式f(x)用F(x)除所得的余式为 <img src='https://img2.soutiyun.com/ask/2020-07-30/964972727738352.png' />

设矩阵<img src='https://img2.soutiyun.com/ask/2020-12-16/976985818130937.png' />证明 (1)<img src='https://img2.soutiyun.com/ask/2020-12-16/976985833829835.png' />的充分必要条件是<img src='https://img2.soutiyun.com/ask/2020-12-16/976985850216772.png' />： (2)当<img src='https://img2.soutiyun.com/ask/2020-12-16/976985874079137.png' />时，A是不可逆矩阵

设a₁,a₂,a₃为正数<img src='https://img2.soutiyun.com/ask/2020-11-28/975436278461242.png' />1＞<img src='https://img2.soutiyun.com/ask/2020-11-28/975436278461242.png' />2＞<img src='https://img2.soutiyun.com/ask/2020-11-28/975436278461242.png' />3.证明:方程 <img src='https://img2.soutiyun.com/ask/2020-11-28/975436328089081.png' /> 在区间(<img src='https://img2.soutiyun.com/ask/2020-11-28/975436278461242.png' />1,<img src='https://img2.soutiyun.com/ask/2020-11-28/975436278461242.png' />2)与(<img src='https://img2.soutiyun.com/ask/2020-11-28/975436278461242.png' />2,<img src='https://img2.soutiyun.com/ask/2020-11-28/975436278461242.png' />3)内各有一根.