Tìm x biết: 3*(2*x-1)*(x+2)-2*(3*x+2)*(x-4)=5 mong mn giúp ạ

Đáp án:

`3 (2x – 1) (x + 2) – 2 (3x + 2) (x – 4) = 5`

`⇔ 3 [(2x – 1) (x + 2)] – 2 [(3x + 2) (x-4)] = 5`

`⇔ 3 [2x (x + 2) – 1 (x + 2)] – 2 [3x (x-4) + 2 (x-4)] = 5`

`⇔ 3 [2x^2 + 4x – x – 2] – 2 [3x^2 – 12x + 2x – 8] = 5`

`⇔ 3 [2x^2 + 3x – 2] – 2 [3x^2 – 10x – 8] = 5`

`⇔ 6x^2 + 9x – 6 – 6x^2 + 20x + 16 = 5`

`⇔ (6x^2 – 6x^2) + (9x + 20x) + (-6 + 16) = 5`

`⇔ 29x + 10 = 5`

`⇔ 29x=5-10`

`⇔29x =-5`

`⇔x=-5 ÷ 29`

`⇔x=(-5)/29`

Vậy `x=(-5)/29`