helppppppppppppppppp mn giúp tuiii vs

Đáp án `+` Giải thích các bước giải:

`c) A + B`

`= x^2 - 2yz + z^2 + 3yz + 5x^2 - z^2 `

`= (x^2 + 5x^2) + (-2yz + 3yz) + (z^2 - z^2) `

`= 6x^2 + yz`

`A - B`

`= x^2 - 2yz + z^2 - (3yz + 5x^2 - z^2) `

`= x^2 - 2yz + z^2 - 3yz - 5x^2 + z^2 `

`= (x^2 - 5x^2) + (-2yz - 3yz) + (z^2 + z^2) `

`= -4x^2 - 5yz + 2z^2`

`d) A + B`

`= 1/2 x^2y + xy^3 - 5/2 x^3y^2 + x^3 + 7/2 x^3y^2 - 1/2 x^2y + xy^3`

`= (1/2x^2y - 1/2x^2y) + (xy^3 + xy^3) + (-5/2 x^3y^2 + 7/2x^3y^2) + x^3`

`= 2xy^3 + x^3 y^2 + x^3`

`A - B`

`= 1/2 x^2y + xy^3 - 5/2 x^3y^2 + x^3 - (7/2 x^3y^2 - 1/2 x^2y + xy^3)`

`= 1/2 x^2y + xy^3 - 5/2 x^3y^2 + x^3 - 7/2 x^3y^2 + 1/2 x^2y - xy^3`

`= (1/2x^2y + 1/2x^2y) + (xy^3 - xy^3) + (-5/2 x^3y^2 - 7/2x^3y^2) + x^3`

`= x^2y -6 x^3y^2 + x^3`