helppppppppppppppppp mn giúp tuiii vs

`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 + 5yz`

`A-B`

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

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

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

`d) A+B`

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

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

`= 2xy^3 - 3/2 x^3 y^2`

`A-B`

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

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

`=  1/4 x^2 y- 17/2 x^3 y^2`