Giải giúp e vs ạ e cảm ơn

Bài `3`

`(x-2)^3+(x+2)^3`

`=[(x-2)+(x+2)].[(x-2)^2-(x-2).(x+2)+(x+2)^2]`

`=2x.[x^2-4x+4-x^2+4+x^2+4x+4]`

`=2x.[x^2+12]`

`=2x^3+24x`

`d)`

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

`=[(x+2y)-(x-2y)].[(x+2y)^2+(x+2y).(x-2y)+(x-2y)^2]`

`=4y.[x^2+4xy+4y^2+x^2-4y^2+x^2-4xy+4y^2]`

`=4y.(3x^2+8y^2)`

`=12x^2y+8y^3`

`g)`

`(2x-3)^3-2x.(2x+1)^2`

`=8x^3-36x^2+54x-27-2x.(4x^2+4x+1)`

`=8x^3-36x^2+54x-27-8x^3-8x^2-2x`

`=-44x^2+52x-27`

HĐT `:`

`a^3+b^3=(a+b).(a^2-ab+b^2)`

`a^3-b^3=(a-b).(a^2+ab+b^2)`

`(a-b)^3=a^3-3a^2b+3ab^2-b^3`

`(a+b)^2=a^2+2ab+b^2`