May be noob question.

Can someone please explain the second decomposition in calculating E2?

i.e. how sigma(6*x2*y*T[x,y,z]) = sigma((3*x2*y+6*y2*x)*T[x,y,z])

May be noob question. Can someone please explain the second decomposition in calculating E2? i.e. how sigma(6x2yT[x,y,z]) = sigma((3x2y+6y2x)T[x,y,z])