∫xdx=x²/2,∫ydy=y²/2,∫1dy=y
二：积分号上x下0,8xydy
= 8x(积分号上x下0,ydy)
= 8x(y²/2)(带入上限 x 减 下限0)
= 8x(x²-0²)/2
= 4x³
一：积分号上1下0,积分号上2下0,1/2,xdydx
= (1/2)(积分号上1下0,xdx)(积分号上2下0,1dy)
= (1/2)[(x²/2)(带入上限1减下限0)][(y)带入上限2减下限0]
= (1/2)[(1²-0²)/2][2-0]
= 1/2
概率论与数理统计用到的微积分知识