z=min(x,y),求EZ
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(x+y-z)/z=(y+z-x)/x=(z+x-y)/y[x+y]/z-1=[y+z]/x-1=[z+x]/y-1[x+y]/z=[y+z]/x=[z+x]/y设[x+y]/z=[y+z]/x=[z
你写错了min=x+y+z;x+y+z>=687;x+y+z>=983;x+y+z>=674;x+y+z>=918;x+y+z>=1206;
EZ=E(x-2y+7)=EX-2EY+7=-3-4+7=0DZ=D(x-2y+7)=DX+D(2y)+D(7)=DX+4DY=5
x/(y+z)=y/(x+z)=z/(x+y)当x+y+z=0时,x+y=-z(x+y)/z=-z/z=-1当x+y+z≠0时,由x/(y+z)=y/(x+z)=z/(x+y)根据等比性质可得(x+y
设(x+y-z)/z=(x-y+z)/y=(-x+y+z)/x=k则(1)x+y-z=kz(2)x-y+z=ky(3)-x+y+z=kx(1)+(2)+(3)得x+y+z=k(x+y+z)∴k=1时,
∵y+z÷x=Z+X÷y=X+Y÷z容易发现x,y,z位置互换也成立∴式子与x,y,z值无关∴x=y=z∴(X+Y-Z)÷(X+Y+z)=x/3x=1/3明教为您解答,请点击[满意答案];如若您有不满
A=全集-{X=z}求概率,加个P就好了呀!
应该要求X_n独立同分布.X服从指数分布,从而由定义知,F(x)=积分从0到x{yexp(-ys)ds}=1-exp(-yx)Z=min{x_i},从而P(Z=z,x2>=z,...xn>=z)=1-
F(z)=P(Z≤z)=P(min(X,Y)≤Z)=1-P(min(X,Y)>Z)=1-P(X>Z,Y>Z)=1-P(X>Z)P(X>Z)=1-[1-P(X≤Z)][1-P(Y≤Z)]=1-[1-F1
EX=3DX=3EY=5DY=2.5EZ=-7DZ=13
设:(x+y-z)/z=(y+z-x)/x=(z+x-y)/y=k{x+y-z=kz(1){y+z-x=kx(2){z+x-y=ky(3)(1)+(2)+(3)得:(x+y+z)=k(x+y+z)(x
令(y+z)/x=(z+x)/y=(x+y)/z=ky+z=kxx+z=kyx+y=kz2(x+y+z)=k(x+y+z)2(x+y+z)=k(x+y+z)(2-k)(x+y+z)=0(x+y+z≠0
ə是偏微分符号əz、əx表示偏微分,əz/əx表示函数z对x的偏导数əz/əx=2xe^(x+y)+x^2e^(x+y)=(x^2
已知z=z(x,y)是由方程sinz=xyz所确定的隐函数.对sinz=xyz方程两边同对x求偏导,于是有cosz*(əz/əx)=yz+xy*(əz/əx).
如果按正常方法做,我们想maxU(x,y,z)约束条件是 pxX+pyY+pzZ=m.建立Lagrangian方程 &n
eZ/eX=2x*[ef(x*x-y*y)/ex],eZ/eY=-2x*[ef(x*x-y*y)/ey],
Z=min(x,y)表示:Z为x、y中较小的概率设A={x=k,y
方程两边同时对x求导得:y(2z∂z/∂x)-(z+x∂z/∂x)=0∴∂z/∂x=z/(2yz-x)
对左右两边求导:(1+ez)dz=ydx+xdy.dz=1/(1+ez).(ydx+xdy).