∵-1/2a²b*(x-1)与1/3a*xb*(y-1)的和是单项式
∴2+x-1=x+y-1
y=2
则:x=2
∴-1/2a²b*(x-1)+1/3a*xb*(y-1)
=-1/2a²b*(2-1)+1/3a²b*(2-1)
=-1/2a²b+1/3a²b
=-1/6a²
∵-1/2a²b*(x-1)与1/3a*xb*(y-1)的和是单项式
∴2+x-1=x+y-1
y=2
则:x=2
∴-1/2a²b*(x-1)+1/3a*xb*(y-1)
=-1/2a²b*(2-1)+1/3a²b*(2-1)
=-1/2a²b+1/3a²b
=-1/6a²