单选题微分方程y″-4y′+5y=0的通解为( )。A ex(C1cos2x+C2sin2x)B C1e-x+C2e5xC e2x(C1cosx+C2sinx)D C1ex+Ce-5x...
Friday, December 1, 2023
问答题设A是n阶方阵,AAT=E,|A|<0,求|A+E|,其中AT是A的转置矩阵....
Monday, December 11, 2023
填空题若物体的运动规律为s=3sin2t,则其在t=0时的速度等于____,加速度为____。...
Tuesday, May 14, 2024
设分别自总体N(μ1,σ2)和N(μ2,σ2)中抽取n1、n2(n1、n2均大于1)的两独立样本,其样本方差分别为S12...
Thursday, September 22, 2022
设随机变量X服从正态分布N(μ1,σ12),Y服从正态分布N(μ2,σ22),且P{|X-μ1|<1}>P{|Y-μ2|...
Wednesday, September 21, 2022
已知方程x2y2+y=1(y>0)确定y为x的函数,则( )。...
Friday, September 16, 2022
设A是m×n矩阵,C是n阶可逆矩阵,矩阵A的秩为r,矩阵B=AC的秩为r1,则( )。...
Friday, September 16, 2022
问答题设A=[aij]3×3是三阶非零矩阵,而且满足aij=-Aij(i,j=1,2,3),其中Aij为行列式|A|中aij的代数余子式,求行列式|A|的值。...
Thursday, November 16, 2023
问答题对于两个随机变量X、Y,若E(X2)及E(Y2)都存在,证明:[E(XY)]2≤E(X2)E(Y2)....
Tuesday, November 21, 2023
填空题方程y″+16y=sin(4x+a)(a是常数)的特解形式为y*=____。...
Sunday, August 20, 2023
问答题求过点M(-1,0,1)且垂直于直线(x-2)/3=(y+1)/(-4)=z/1又与直线(x+1)/1=(y-3)/1=z/2相交的直线方程。...
Thursday, September 21, 2023
设三向量a(→),b(→),c(→)满足关系a(→)·b(→)=a(→)·c(→),则( )。...
Wednesday, September 21, 2022
如果二阶常系数非齐次线性微分方程y″+ay′+by=e-xcosx有一个特解y*=e-x(xcosx+xsinx),则(...
Wednesday, September 21, 2022
设函数u=u(x,y)满足∂2u/∂x2-∂2u/∂y2=0及条件u(x,2x)=x,ux′(x,2x)=x2,u有二阶...
Wednesday, September 21, 2022
设z=e-x-f(x-2y),且当y=0时,z=x2,则∂z/∂x=____。...
Wednesday, September 21, 2022
n维向量组,α1,α2,…,αs(3≤s≤n)线性无关的充要条件是( )....
Sunday, September 18, 2022
填空题设函数y=1/(2x+3),则y(n)(0)=____。...
Wednesday, January 31, 2024