Giúp vs mn ơiiiiii :))))

`P=(5x-1)-2(1-5x)(4+5x)+(5x+4)^2`

`=(5x-1)-2(4+5x-20x-25x^2)+(25x^2+40x+16)`

`=5x-1-8-10x+40x+50x^2+25x^2+40x+16`

`=75x^2+75x+7`

`Q=(x-y)^3+(y+x)^3-(y-x)^3+3xy(x+y)`

`=(x-y)^3+(x+y)^3+(x-y)^3+3xy(x+y)`

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

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

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

`=3x^3+12xy^2-y^3`

`A=(x-2)^3-x(x+1)(x-1)+6x(x-3)`

`=(x^3-6x^2+12x-8)-x(x^2-1)+(6x^2-18x)`

`=x^3-6x^2+12x-8-x^3+x+6x^2-18x`

`=-5x-8`

`B=(x-3)^3-x^2(x-9)+27`

`=(x^3-9x^2+27x-27)-(x^3-9x^2)+27`

`=x^3-9x^2+27x-27-x^3+9x^2+27`

`=27x`