Question

Tìm x

Căn(6x^2-4x)-x=3

Answer 1

\(\Leftrightarrow\left\{{}\begin{matrix}x>=-3\\\left(6x^2-4x-x-3\right)\left(6x^2-4x+x+3\right)=0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x>=-3\\\left(6x^2-5x-3\right)=0\end{matrix}\right.\)

hay \(x=\dfrac{5\pm\sqrt{97}}{12}\)

Answer 2

`\sqrt{6x^2-4x}-x=3`

`<=>\sqrt{6x^2-4x}=3+x`      `ĐK: x >= -3`

`<=>6x^2-4x=9+6x+x^2`

`<=>5x^2-10x-9=0`

`<=>5(x^2-2x-9/5)=0`

`<=>x^2-2x+1-14/5=0`

`<=>(x-1)^2=14/5`

`<=>|x-1|=\sqrt{70}/5`

`<=>x=[5+-\sqrt{70}]/5` (t/m)

Vậy `S={[5+-\sqrt{70}]/5}`