∫∫f(u,v)dudv 是一个数,记为 A,
则 f(x,y) = xy+A,两边在D上作二重积分,得
∫∫f(x,y)dxdy =∫∫xydxdy + A∫∫dxdy
即 A = ∫∫xydxdy + Aσ
A =∫xdx∫ydy + A∫x^2dx
=∫x^5/2dx + A/3,
得 2A/3 = 1/12,A=1/8,
则 f(x,y) = xy+1/8.
∫∫f(u,v)dudv 是一个数,记为 A,
则 f(x,y) = xy+A,两边在D上作二重积分,得
∫∫f(x,y)dxdy =∫∫xydxdy + A∫∫dxdy
即 A = ∫∫xydxdy + Aσ
A =∫xdx∫ydy + A∫x^2dx
=∫x^5/2dx + A/3,
得 2A/3 = 1/12,A=1/8,
则 f(x,y) = xy+1/8.