-If the sum of 2A ^ XB ^ 2-y and 1 / 2A ^ 2B ^ 5 is a monomial, then the value of polynomial 1 / 2x ^ 3-1 / 6xy ^ 2 + 1 / 3Y ^ 2 is____ ?

-If the sum of 2A ^ XB ^ 2-y and 1 / 2A ^ 2B ^ 5 is a monomial, then the value of polynomial 1 / 2x ^ 3-1 / 6xy ^ 2 + 1 / 3Y ^ 2 is____ ?

-The sum of 2A ^ XB ^ 2-y and 1 / 2A ^ 2B ^ 5 is a monomial
x=2,2-y=5
y=-3
1/2x^3-1/6xy^2+1/3y^2
=½×8-1/6×2×9+1/3×9
=4-3+3
=4