P=x•z^2 O=(x^2)•y-5 R=-4xy+(y^2)•z根据高斯公式原式=∫∫∫(x^2+y^2+z^2)dv=∫(0,2π)dθ∫(0,π/2)sinφdφ∫r^4dr=2π×(1/5)=2π/5
