Ch3-99 2n0G,1P3s1 2O1√2丌O2 故P=0 一将ρ=0代入f(x,y)即得 f(x,y)=f(xf(yCh3-99 1 2 2 1 2 2 1 2 1 2 1 1      = − 故  = 0 将  = 0 代入 f (x, y) 即得 f (x, y) f (x) f ( y) = X Y