设随机变量(X，Y)的分布函数F(x，y)=1/π2[π/2+arctan(x/3)][π/2+arctan(y/2)]，则(X

设随机变量(X，Y)的分布函数F(x，y)=1/π²[π/2+arctan(x/3)][π/2+arctan(y/2)]，则(X，Y)的概率密度为____．
【正确答案】：f(x,y)=6/[π²(9+x²)(4+y²)]

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