Giúp mình bài 6, 7 vs ạ. Nhanh và đúng mik vote 5 sao ạ

` \color{#0074D9}{#n}\color{#0088DD}{q}\color{#3399FF}{o}\color{#66AAFF}{c}\color{#99CCFF}{c} `

Bài `6`

`a) -2x(x+3) + x(2x - 1) = 10 `

`-2x^2 - 6x + 2x^2 - x = 10 `

`(-2x^2 + 2x^2) + (-6x - x) = 10 `

`-7x = 10 `

`=> x = -10/7`

Vậy ` x = -10/7`

`b) (2/3x)(9x/2 + 1/4) - (3x^2 + x + 2) = 3 `

`3x^2 + 1/6 - 3x^2 - x - 2 = 3 `

`1/6x - x - 2 = 3 `

`-5/6x - 2 = 3 `

`-5/6x = 5 `

`=> x = -6 `

Vậy ` x = - 6 `

Bài `7`

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

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

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

`= (x-y)^3 `

`b) -(x-y)(x^2 + xy - 1) `

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

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

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

`c) -(x^2 - 2y)(x+y^2 - 1) `

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

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

`d) (1/2x - 1)(2x -3) `

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

`=x^2 - 7/2x + 3 `