[单选题]将2(x+y)-3(x-y)-4(x+y)+5(x-y)-3(x-y)合并同类项得()。A.-3x-yB.-2(x+y)C.-x+yD.-2(x+y)
[单选题]将2(x+y)-3(x-y)-4(x+y)+5(x-y)-3(x-y)合并同类项得()。A.-3x-yB.-2(x+y)C.-x+yD.-2(x+y)
[单选题]设(x-y)(x+2+y)-15=0,则x+y的值是()。A.-5或3B.-3或5C.3D.5
[单选题]如果X与Y满足D(X+Y)=D(X-Y),则必有()。A.X与Y相互独立B.X与Y不相关C.D(Y)=0D.D(X)·D(Y)=0
[单选题]若X=-127,Y=-1,字长N=8,则[X+Y]补是A.80HB.00HC.0FDHD.7EH
[单选题]已知D(X)=2,D(Y)=3,则Cov(X+Y,X-Y)等于().A . 1B . -1C . 5D . 6
[问答题]D(X)=4,D(Y)=9,ρXY=0.5,则D(X-Y)=----------,D(X+Y)=------------.
[问答题]D(X)=4,D(Y)=9,ρXY=0.5,则D(X-Y)=-------------,D(X+Y)=-------------.
[单选题]已知D:x+y≤1,D1:x≥0,y≥0,x+y≤1,,则()。A . I=JB . I=2JC . I=3JD . I=4J
[单选题]设[X]补=1111111111100001,[Y]补=1111111111111000,则[X-Y]补的结果是( )A.1111111111101001B.0000000000111100C.1111111111111000D.0000000000111101