Giải cho tôi bài tập này

`2,9x^2 - 1/16y^2=(3x)^2 - (1/4y)^2=(3x - 1/4y)(3x + 1/4y)`

`3,x^6 - y^4=(x^3)^2 - (y^2)^2=(x^3 - y^2)(x^3 + y^2)`

`5,81 - (3x + 2)^2=9^2 - (3x + 2)^2=(9 - (3x + 2))(9 + (3x + 2))`

`6,9(x - 5y)^2 - 16(x + y)^2=(3(x - 5y))^2 - (4(x + y))^2=(3(x - 5y) - 4(x + y))(3(x - 5y) + 4(x + y))`

`8,27x^3 + 125y^3=(3x)^3 + (5y)^3=(3x + 5y)(9x^2 - 15xy + 25y^2)`

`9,x^6 + 216=(x^2)^3 + 6^3=(x^2 + 6)(x^4 - 6x^2 + 36)`

`11,9x^2 - 12xy + 4y^2=(3x)^2 - 23x2y + (2y)^2=(3x - 2y)^2`

`12,25x^2y^2 + 10xy - 1=(5xy)^2 + 25xy1 - 1^2=(5xy - 1)(5xy + 1)`

`14,8x^3 + 12x^2y + 6xy^2 + y^3=(2x + y)(4x^2 + 2xy + y^2)=(2x + y)(2x + y)^2`

`16,x^10 - 1=(x^5)^2 - 1^2=(x^5 - 1)(x^5 + 1)`

`18,4x^2 - 25=(2x)^2 - 5^2=(2x - 5)(2x + 5)`

`19,x^4 - y^4=(x^2)^2 - (y^2)^2=(x - y)(x + y)(x^2 + y^2)`

`21,x^2 + 6x - 9=-(x^2 - 6x + 9)=-(x - 3)^2`

`22,x^2 + 4xy + 4y^2=x^2 + 2*2xy + (2y)^2=(x + 2y)^2`

`24,(x + y + z)^2 - 4z^2=(x + y + z)^2 - (2z)^2=(x + y - 2z)(x + y + 2z)`

`25,(3x + 1)^2 - (x + 1)^2=(3x + 1 - (x + 1))(3x + 1 + (x + 1))=(2x)(4x + 2)`

`27,8x^3 - y^3 - 6xy(2x - y)=8x^3 - 12x^2y + 6xy^2 - y^3=(2x - y)(4x^2 - 2xy + y^2)`

`@612009`