dfrac ((x+1)+i(y-3))(5+3i)=1+i ，则实部dfrac ((x+1)+i(y-3))(5+3i)=1+i，虚部 dfrac ((x+1
设复数_(1)=(x)_(1)+i(y)_(1), _(2)=(x)_(2)+i(y)_(2)，且_(1)=(x)_(1)+i(y)_(1), _(2)=(x)
3.设X_(1),...,X_(10)为来自标准正态总体Xsim N(0,1)，Y_(1)=7sum_(i=1)^3X_(i)^2,Y_(2)=3sum_(i=
设_(xy)=sum _(i=1)^4((x)_(i)-overline (x))((y)_(i)-overline (y))，_(xy)=sum _(i=1)
22.(1)设随机变量X 1,X2,X3,X4相互独立,且有 ((X)_(i))=i ,((X)_(i))=5-i i=1 ,2,3,4.设 Y=-|||-.(
求变力F=(-2x+y)i+(y-3 x)→(3)将质点沿圆F=(-2x+y)i+(y-3 x)→(3)的正向转动一周所做的功求变力将质点沿圆的正向转动一周所做
22 （1）设随机变量X_(1),X_(2),X_(3),X_(4)相互独立，且有E(X_(i))=i,D(X_(i))=5-i,i=1,2,3,4.设Y=2X
令 Y = (1)/(n) sum_(i=1)^n X_i，则A. $\Cov(X_1, Y)= \frac{\sigma^2}{n}$.B. $Cov(X_1
14、设5个灯泡的寿命X_(i)(i=1,...,5)独立同分布，且E(X_(i))=a，D(X_(i))=b,(i=1,...,5)，则5个灯泡的平均寿命Y=
5.试判断下列函数的可微性和解析性:-|||-(1) (z)=x(y)^2+i(x)^2y ;-|||-(2) (z)=(x)^2+i(y)^2 ;-|||-(