If X and Y are random variables with E(X) =5 and E(Y) = 8, then E(2X + 3Y) is:
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- 汉语水平考试
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1.If X and Y are random variables with E(X) =5 and E(Y) = 8, then E(2X + 3Y) is:
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2.微分方程y''-4y' 13y=0, y| x = 0 =0, y¢| x = 0 =3.的特解是______A.y=e 2x sin3xB.y=C 1 e 2x sin3xC.y=e 2x sinxD.y
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3.e>e(x≠y
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4.y=e的-x2的次方,()=(-2x)e的x次方
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5.Vx(7E(x,o)> ( y(E(y, g(x))A ze(z, g(x))> E(y, z))
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6.设随机变量X与Y相互独立,且E(X)与E(Y )存在,记U = max(X, Y), V = min(X, Y ),则 E(UV ) =( ).
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7.曲线 2 2 1 1 x x e y e -
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8.若y(n)=x(n)h(n),则Y(e^jw)=X(e^jw)H(e^jw).
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9.If and only if x=ln(y), y=e^x.
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10.若随机变量X与Y的二阶矩有E[XY] = 0,则E[X]E[Y] = 0