• 2022-06-01 问题

    已知X,Y的联合概率密度为f(x,y)=kxy,0≤x≤1,0≤y≤1求(1)常数k,(2)联合分布函数F(x,y)(3)概率P(X≤Y)

    已知X,Y的联合概率密度为f(x,y)=kxy,0≤x≤1,0≤y≤1求(1)常数k,(2)联合分布函数F(x,y)(3)概率P(X≤Y)

  • 2022-06-11 问题

    (多选)以下平面弹性体的位移或形变状态不可能存在的是 A: 位移分量$u = {k_1}\left( {{x^2} + {y^2}} \right),v = {k_2}xy$(${k_1},{k_2}$为常数) B: ${\varepsilon _x} = k\left( {{x^2} + {y^2}} \right),{\varepsilon _y} = k{y^2},{\gamma _{xy}} = 2kxy$(${k \ne 0}$) C: ${\varepsilon _x} = 0,{\varepsilon _y} = 0,{\gamma _{xy}} = kxy$(${k \ne 0}$) D: ${\varepsilon _x} = ax{y^2},{\varepsilon _y} = b{x^2}y,{\gamma _{xy}} = cxy$($a \ne 0,b \ne 0,c \ne 0$)

    (多选)以下平面弹性体的位移或形变状态不可能存在的是 A: 位移分量$u = {k_1}\left( {{x^2} + {y^2}} \right),v = {k_2}xy$(${k_1},{k_2}$为常数) B: ${\varepsilon _x} = k\left( {{x^2} + {y^2}} \right),{\varepsilon _y} = k{y^2},{\gamma _{xy}} = 2kxy$(${k \ne 0}$) C: ${\varepsilon _x} = 0,{\varepsilon _y} = 0,{\gamma _{xy}} = kxy$(${k \ne 0}$) D: ${\varepsilon _x} = ax{y^2},{\varepsilon _y} = b{x^2}y,{\gamma _{xy}} = cxy$($a \ne 0,b \ne 0,c \ne 0$)

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