1) 2у^3+8y-11-(3y^3-6y+3) 2) y^3-y+7-(y^3+5y+11) 3) 15-7y^2-(y^3-y^2-15) 4) 12c^2g-3cg^2+4-(6c^2g-5cg+2c) 5) c^2+2cg+g^2-(5c^2-6cg-7g^2)

1) 2y^3+8y-11-3y^3+6y-3=-y^3+14y-14,
2) y^3-y+7-y^3-5y-11=-6y-4,
3)15-7y^2-y^3+y^2+15=-y^3-6y^2+30,
4) 12c^2g-3cg^2+4-6c^2g+5cg-2c=6c^2g-3cg^2+5cg-2c+4,
5) c^2+2cg+g^2-5c^2+6cg+7g^2=-4c^2+8cg+8g^2.