由:E(X/2-1)=E(X)/2 - 1=1 推出:
E(X)=4;
由:D(-X/2+1)=D(-X/2)=D(X/2)=D(X)/4=2,推出:
D(X)=8;
求:
E(2X²)=2E(X²)=2[D(X)+E²(X)]=2[8+4²]=48;
E(3X²)=3E(X²)=72.
由:E(X/2-1)=E(X)/2 - 1=1 推出:
E(X)=4;
由:D(-X/2+1)=D(-X/2)=D(X/2)=D(X)/4=2,推出:
D(X)=8;
求:
E(2X²)=2E(X²)=2[D(X)+E²(X)]=2[8+4²]=48;
E(3X²)=3E(X²)=72.