M+N=x3-xy2+3y3+3/2+2x3+y3-2
=(x3+2x3)+(3y3+y3)+(3/2-2)-xy2
=3x3+4y3-1/2-xy2
M-N=x3-xy2+3y3+3/2-(2x3+y3-2)
=x3-xy2+3y3+3/2-2x3-y3+2
=(x3-2x3)+(3y3-y3)+(3/2+2)-xy2
=-x3+2y3+7/2-xy2
N-M=2x3+y3-2-(x3-xy2+3y3+3/2)
=2x3+y3-2-x3+xy2-3y3-3/2
=(2x3-x3)+(y3-3y3)+(-2-3/2)+xy2
=x3-2y3-7/2+xy2
A=x2-5+xy-y-(2x2+xy-1)
=x2-5+xy-y-2x2-xy+1
=(x2-2x2)+(xy-xy)+(-5+1)-y
=-x2-4-y
B=xy-5-x3+6x2y2+x3+2
=xy-(-5+2)+(-x3+x3)+6x2y2
=xy+3+6x2y2
