(1+e)-|||-D.2
-1 . C.0 D.2
-2-|||-D.2
sqrt (2) D.2如,两相干波源Sl和S2向右发出两列振幅都为A0,波长均为的平面简谐波,两波源相距,Sl的相位比S2超前.则看看看看
sqrt (2) C. sqrt (3) D.2
(int )_(0)^1dfrac (1)(2)xdx= A.1B.0C.(int )_(0)^1dfrac (1)(2)xdx=D.2A.1B.0C.D.2
已知点A(1,2),B(a,3), |AB|=sqrt (10),则A(1,2),B(a,3), |AB|=sqrt (10).A.-2 B.4 C.-2或4
已知X~N(2,4),则((X)^2)=A.8 B.6 C.4 D.2已知X~N(2,4),则=A.8B.6C.4D.2
函数 (x)=(x+1)(|)^2-1| ()-|||-A.1个驻点,1个极值点, B.1个驻点,2个极值点,-|||-C.2个驻点,1个极值点, D.2个驻点
已知_(1)=((a,1,1))^T, (alpha )_(2)=((-1,-1,2))^T是三阶实对称矩阵属于两个不同特征值的特征向量,则a=____.A.1