设(X,Y)的联合密度为f(x,y)={Ax^2y, 0<x<y<1;0,其他) 求常数A答:∫f(x,y)dxdy =∫∫[0,1][x,1]Ax^2ydxdy =∫[0,1]Ax^2y^2/2[x,1]dx =∫[0,1](Ax^2/2-Ax^4/2)dx =(Ax^3/6-Ax^5/10)[0,1]=A/6-A/10 =A/15=1 A=15
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