Question

Tìm x,biết a,3x²-5x-2=0

Answer 1

\(3x^2-5x-2=0< =>3x^2-6x+x-2=0< =>3x\left(x-2\right)+\left(x-2\right)=0< =>\left(x-2\right)\left(3x+1\right)=0< =>\left[{}\begin{matrix}x-2=0\\3x+1=0\end{matrix}\right.< =>\left[{}\begin{matrix}x=2\\x=-\dfrac{1}{3}\end{matrix}\right.\)

Answer 2

`3x^2-5x-2=0`

`=> 3x^2-6x+x-2=0`

`=> 3x(x-2)+(x-2)=0`

`=>(x-2)(3x+1)=0`

Trường hợp `1`

`x-2=0`

`=> x=0+2`

`=> x=2`

Trường hợp `2`

`3x+1=0`

`=> 3x=0-1`

`=> 3x=-1`

`=> x=(-1)/3`

`=> x=-1/3`

Vậy `x in {2;-1/3}`