Giúp mình 2 bài này với mình đang cần gấp mình sẽ đánh giá tốt ah

Bài 3:

`a)3x^2yz(2xyz)`

`=6x^3y^2z^2`

`b)(4x-3)(x+1)`

`=4x(x+1)-3(x+1)`

`=4x^2+4x-3x-3`

`=4x^2+x-3`

`c)(3x-y-2)xy`

`=3x*xy-y*xy-2*xy`

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

`d)(x-y)(x+y)`

`=x(x+y)-y(x+y)`

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

`=x^2-y^2`

`e)(x+y)^2`

`=(x+y)(x+y)`

`=x(x+y)+y(x+y)`

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

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

`g)(x-y)^2`

`=(x-y)(x-y)`

`=x(x-y)-y(x-y)`

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

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

`h)(x+y)^3`

`=(x+y)(x+y)^2`

`=(x+y)(x^2+2xy+y^2)`

`=x(x^2+2xy+y^2)+y(x^2+2xy+y^2)`

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

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

`k)(x-y)^3`

`=(x-y)(x-y)^2`

`=(x-y)(x^2-2xy+y^2)`

`=x(x^2-2xy+y^2)-y(x^2-2xy+y^2)`

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

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

`q)(x+y+z)^2`

`=(x+y+z)(x+y+z)`

`=x(x+y+z)+y(x+y+z)+z(x+y+z)`

`=x^2+xy+xz+xy+y^2+yz+zx+zy+z^2`

`=x^2+y^2+z^2+2xy+2yz+2xz`

Bài 4:

`1)`

`a)A+B=x+5`

`(x^3-4x+3)+B=x+5`

`B=(x+5)-(x^3-4x+3)`

`=x+5-x^3+4x-3`

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

`b)A-B=x^3-3x`

`(x^3-4x+3)-B=x^3-3x`

`B=x^3-4x+3-x^3+3x`

`=-x+3`

`c)A:B=x+1`

`B=A:(x+1)`

`=(x^3-4x+3)/(x+1)`

`2)`

`a)M-N=x-xy`

`(2xy+x-y+3)-N=x-xy`

`N=2xy+x-y-x+xy`

`=3xy-y`

`b)M+N=y+3`

`(2xy+x-y+3)+N=y+3`

`N=y+3-2xy-x+y-3`

`=-2xy+2y-x`

`c)M:N=(x+y-1)`

`N=M/(x+y-1)`

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